Download Enso - Earth and Atmospheric Sciences

Tom Snyder Productions
®
™
El Niño
™
Developed by Planet Earth Science
with support from
the National Aeronautic and Space Administration
and the Department of Energy
PLANET
EARTH
S C I E N C E
Published by Tom Snyder Productions
Tom Snyder Productions is the leading provider of interactive group software products that enable teachers to use technology
to increase student understanding, knowledge, and problem-solving capabilities. This unique approach — which motivates
students to interact with each other, rather than a machine — not only improves overall academic performance, but also fosters lifelong communication, decision-making, and collaboration skills. The company’s product line spans the K–12 curriculum in the areas of social studies, science, math, and language arts.
© 1998 Planet Earth Science, Inc. Ocean Expeditions: El Niño is a trademark of Planet Earth Science, Inc. Tom Snyder Productions is
a registered trademark of Tom Snyder Productions, Inc. Macintosh and QuickTime are registered trademarks of Apple Computer, Inc.
Windows is a registered trademark of Microsoft Corporation.
This document and the software described in it may not, in whole or part, be copied, photocopied, reproduced, translated,
or reduced to any electronic medium or machine-readable form other than that which has been specified herein without
prior written consent from Tom Snyder Productions, Inc.
For further information about this product, or for a free Tom Snyder Productions catalog, please call us at
1-800-342-0236
Contents
Credits ........................................................................................................................................................4
Overview ....................................................................................................................................................5
Program Goals ......................................................................................................................................5
A New Approach: Earth System Science ................................................................................................5
Using the Software ......................................................................................................................................6
Hardware Requirements ........................................................................................................................6
Memory Requirements ..........................................................................................................................6
Software Installation ............................................................................................................................6
Macintosh Network Instructions ............................................................................................................6
Performance Tips ..................................................................................................................................8
Navigating the Ship ..............................................................................................................................9
Understanding the Ocean Expeditions Process ..........................................................................................12
The Scenario ......................................................................................................................................12
Student Roles and Materials ................................................................................................................12
The Classroom Process ........................................................................................................................13
Managing the Classroom Experience ..........................................................................................................14
Preparing Yourself ..............................................................................................................................14
Organizing Your Classroom..................................................................................................................14
Creating Student Groups ......................................................................................................................15
Assessing Student Performance ................................................................................................................16
Content Objectives ..............................................................................................................................16
Assessment Rubric ..............................................................................................................................16
Suggestions to Fit Your Curriculum ............................................................................................................24
Option I: Thematic Approach ..............................................................................................................24
Option II: National Standards ..............................................................................................................25
Option III: State Frameworks ..............................................................................................................25
Science Framework for California Public Schools ................................................................................26
Detailed Scientific Background ..................................................................................................................27
Introduction to Earth System Science and Global Change ....................................................................27
Tropical Ocean-Atmosphere System ....................................................................................................28
El Niño ..............................................................................................................................................28
Scientific Concepts ..............................................................................................................................30
Sea Surface Temperature......................................................................................................................31
Surface Currents ..................................................................................................................................33
Surface Pressure ..................................................................................................................................35
Surface Wind ......................................................................................................................................37
Clouds/Precipitation ............................................................................................................................38
Ocean Temperature ..............................................................................................................................39
Atmospheric Circulation ......................................................................................................................41
Ocean Circulation ................................................................................................................................42
Appendix: Worksheet Masters ....................................................................................................................43
4
Ocean Expeditions: El Niño
Credits
Developed by Planet Earth Science
Creative Director: David Elam
Content Writers: Diane Schweizer and Dr. Catherine Gautier
Art Director: Karen Shapiro
Graphics and Animation: Karen Shapiro, Nancy Yamamoto, Cullen Davis, and David Elam
EARTH
Concept & Executive Producer: Dr. Catherine Gautier
Marketing & Business Development: Jeannette Gautier-Downes
PLANET
SCIENCE
Programming: Marty Landsfeld
Instructional Design: David Elam, Jeannette Gautier-Downes, and Diane Schweizer
Additional Writers: Brian Bloomfield and R.C.J. Somerville, Ph.D.
Consultants: R.C.J. Somerville, Ph.D., Bernard J. Dodge, Ph.D., and Nan Sterman
P
lanet Earth Science, Inc. develops interactive educational software that bring Earth System Science concepts to life in
classrooms. These dynamic multimedia simulations take advantage of Apple Computer’s QuickTime™ Virtual Reality
technology to engage students in authentic, hands-on experiments where they operate modern research tools and manipulate real
data to conduct global investigations. Using satellite observations of Earth and data from climate models, students explore the
interactions of Earth components and the interconnections of the scientific disciplines: biology, physics, chemistry,
geography, oceanography, meteorology, and climatology. The investigations address important research topics — such as the
El Niño climate phenomenon and the Antarctic ozone hole — and allow students to discover the nature of our changing
planet as well as its impacts on plant and animal life, societies, and economies around the world.
Planet Earth Science programs are designed in collaboration with science teachers and are based on National Science
Education Standards developed by the National Academy of Sciences. They allow students to participate actively in the
scientific process by solving an experimental problem that requires them to establish a hypothesis, collect and analyze
data, and confirm their findings. Visit the Planet Earth Science site at www.PlanEarthSci.com for more resources.
Overview
5
Overview
O
cean Expeditions: El Niño brings Earth System
Science concepts to life in the classroom by challenging your students to conduct modern climate
research as it really happens. This exciting multimedia
learning tool engages students in a journey where they
must navigate their own ship, operate modern research
tools, and manipulate satellite and climate model data to
investigate and help predict El Niño — one of our planet’s
largest global climatic disruptions.
Program Goals
The goals of Ocean Expeditions: El Niño are:
• to give students a strong understanding of the
process of scientific inquiry and confirmation.
• to get students excited about Earth System
Science, the environment, and careers in science.
• to give students a new, global vision of how
the Earth operates as a system of interconnected processes.
• to instill in students an appreciation for how
science and technology play an important role
in our civilization and our relationship to our
everchanging planet.
A New Approach:
Earth System Science
The adventure takes place early in the 21st century.
Students are hired by Dr. Enso, director of the fictitious
Earth Monitoring Organization (EMO), to verify two
conflicting reports about a predicted El Niño event that
poses disastrous consequences for life and economies
around the world. The crew members set sail on the
research vessel Glomar to embark on their own investigation. They follow the scientific method to:
1. Establish a hypothesis on the climate state by
learning about sea surface temperature and climate
patterns.
2. Collect data from satellites and climate models of
pressure, winds, currents, and clouds/precipitation.
3. Analyze data by learning about climate patterns
and comparing present findings to historical data.
4. Substantiate a hypothesis by submitting
supporting evidence and conclusions.
Ocean Expeditions: El Niño uses a new approach to studying Earth. This approach, known as Earth System Science
(or ESS), sees Earth as an evolving system of interacting
components. It emphasizes the interconnections of the
traditional scientific disciplines, such as biology, physics,
chemistry, geography, oceanography, meteorology, and
climate. The notion of considering Earth as an evolving,
interactive system has emerged within the scientific
community during the past few decades. It was led, to a
large degree, by our ability to observe Earth from space, as
well as by a need to better understand climate change and
other global phenomena.
Earth System Science education was introduced into university-level curricula in the early 1990s as a strategy for
conducting global Earth studies and research. Its goal is to
enhance the awareness of climate change and to provide
future scientists with a more global perspective on environmental change.
The Planet Earth Science site at www.PlanEarthSci.com
has many more resources for teachers using this program.
6
Ocean Expeditions: El Niño
Using the Software
Hardware Requirements
Software Installation
To install Ocean Expeditions: El Niño on your Macintosh
computer, you will need the following minimum
equipment and operating software:
You must use the installation program to install Ocean
Expeditions: El Niño on your hard disk. You can’t install
it by dragging it to your hard disk. Follow these installation steps:
• 68040 or higher: System 7.5 or later, with
8MB of available RAM.
1. Disable virus protection and file sharing.
• Power PC: System 7.5.3 or later, with 8MB
of available RAM.
2. Insert the CD-ROM into your CD-ROM drive.
• a double-speed CD-ROM drive or faster.
3. Double-click the file named Installer.
• QuickTime 2.5 or later.
™
• about 20 MB of hard disk space, depending
on your installation choices.
Memory Requirements
The program requires 8 MB of available RAM. You may
need to use the memory feature called Virtual Memory to
ensure that you have enough memory for good performance of the program. Make sure no programs are running, then choose About This Macintosh from the
Apple menu. The system will show you the total memory on your computer and the largest unused block. The
largest unused block must be at least 8 MB.
If your system has a total of 16 MB RAM or less of builtin memory, at least 8 MB RAM must be available for the
program. One way to free up memory is to restart your
computer with only the bare minimum settings (CDROM, QuickTime, and network extensions). Another
option is to use Virtual Memory. It’s possible that Virtual
Memory will make the program slower.
Choose the Memory Control Panel and check the following settings.
• Disk Cache: Make sure the cache size is at least
32 KB for every 1 MB of built-in memory.
• Modern Memory Manager: Make sure it’s on.
• Virtual Memory: If your computer’s available
built-in memory is 16 MB, turn Virtual Memory
on, setting it to the amount of total installed
memory plus 1 MB. If your computer’s available
built-in memory is more than 16 MB, turn Virtual
Memory off.
• RAM Disk: Keep your existing setting.
Restart your computer if you have changed any memory
settings or extensions in effect.
4. Click Continue.
5. Click Accept on the Software License
Agreement screen.
6. Once the Installer screen opens, you must first
use the Location selection menu to select a folder
(or create a new one) in which you will install
the application files.
7. Now follow the directions for: Easy Installation
or Custom Install.
8. For easy installation, simply click the Install
button. This installs the complete application
program and required system extensions.
9. Follow the on-screen instructions.
10. After the installation is complete, click
Quit or Restart.
11. Turn virus protection and file sharing back on.
Macintosh Network Instructions
If you’d like to use the program in a networked environment, you’ll need a CD-ROM for each computer. You’ll
need an Ethernet network, with each computer assigned a
unique IP address. The instructions below walk you
through the technical setup. If your computers have
already been set up for a networked environment, you
should consult your network administrator before changing the network setup.
Using the Software
Step 1: Connect Computers via Ethernet.
• Under the Apple menu, select Control Panels.
• In the Control Panels, select AppleTalk or
Network (only one or the other will be present).
• Select Connect via: Ethernet.
• Close the control panel and save the new setting
when prompted.
• Repeat steps for every computer.
Step 2: Set network protocol as MacTCP
or TCP/IP.
7
• Close the control panel and save the new setting
when prompted.
• Repeat steps for every computer.
Step 3: Set up the Server computer.
• Choose one computer to be the server computer.
Write down the IP address of that computer
(the Server IP address).
• Double-click the El Niño icon on your hard drive
in the Ocean Expeditions ƒ folder.
• Choose New Simulation.
• Type crew and ship names.
• Under the Apple menu, select Control Panels.
• Click Networked.
• In the Control Panels, select MacTCP or TCP/IP
(only one or the other will be present).
• The program automatically places the computer’s
IP address in the field Your IP Address. On the
Server computer, you should enter that same IP
address in the field Server IP Address. Record
this server IP address to use in setting up the
other computers.
• Choose Connect via: AppleTalk (MacIP)
or Ethernet.
Depending on your protocol choice above, you
will have a few different options under Configure.
Find the one applicable to your setup below.
• Connect via: Ethernet, configure Manually.
Check that your computer has an IP address.
If not, you’ll have to assign one (see instructions
below). When you close the control panel, you’ll
be prompted about a subnet mask value. It’s okay
to ignore this message.
• Connect via: AppleTalk (MacIP), configure
Using MacIP Manually. Check that your
computer has an IP address. If not, you’ll have
to assign one (see instructions below).
• Connect via: AppleTalk (MacIP), configure
Using MacIP Server. This means that all your
computers should already be running from a server.
The IP addresses are assigned by the single-server
computer. The only thing you’ll need is the IP
address of that server computer.
• If necessary, assign a unique IP address to every
computer you will be using. An IP address can be
any four numbers, separated by three periods. For
example, you might assign the five computers in
your network the following unique IP addresses:
1.1.1.11, 1.1.1.12, 1.1.1.13, and 1.1.1.14. Do not
use zeros in the address.
• Click Continue Simulation.
• Your computer will display the message Contacting
Server. You are now ready to connect with all of
the other computers.
Step 4: Set up the remaining computers,
one at a time.
• Open the Ocean Expeditions ƒ folder on the hard
drive and have each team double-click the El Niño
icon on their hard drive. Do not try to log on several
computers at the same time.
• Choose New Simulation.
• Each team should type a unique crew and
ship name. Ships must not have duplicate names.
• Click Networked.
• Enter the Server IP Address you recorded earlier.
• Click Continue Simulation. You are now logged
onto a network session and are ready to start.
8
Ocean Expeditions: El Niño
Performance Tips
Turn off all unnecessary extensions. Extra extensions
use up memory and may interfere with the quality of the
audio. (Remember: After resetting your extensions, make
sure to restart your computer.)
Quit other programs before using Ocean Expeditions:
El Niño.
Reposition your speakers and/or monitor. Sound
quality can suffer if your speakers are blocked by, or
touching, a wall or other object. If you are experiencing
sound problems, try moving your speakers. Placing speakers
on a carpet or other soft surface can help reduce vibrations.
Trouble connecting to the Server computer in a
networked setting? Restart the computer and try again. If
the Server computer is unexpectedly down in the middle of
a networked session, choose another computer’s IP address
as the Server computer and use it as the new server.
Improve performance of the software by turning
off file sharing.
Using the Software
Navigating the Ship
Once the CD-ROM is launched, your students will first
need to choose either a new simulation or continue from
a saved file.
Next, your students must sign in both a crew name and a
ship name. The ship name is used by the software to
identify individual e-mail addresses. The crew name is
stored for the teacher to identify a group of students and is
displayed as part of the mission report. Additionally, your
students will have the opportunity to establish a networked
or a non-networked simulation.
9
The last step before your students board the ship is to
enter the name of each crew member and to identify the
climate variable the crew will study. Crew roles are
determined by the booklet that each crew member
receives (Navigator, Data Collector, Data Analyst, or
Communications Expert). The climate variable is determined by the teacher and should match the worksheet that
you give the crew (currents, pressure, winds, or
clouds/precipitation). If more than one crew is using the
program, have each crew study a different variable while
collaborating and sharing information and data. After the
crew signs in, they should select the Continue button and
be on their way!
10
Ocean Expeditions: El Niño
Using QuickTime VR
QuickTime VR Cursor Icons
The ships your students are crewing are the finest in the
international Glomar fleet. Once on board, your students
will enter a three-dimensional world that is much like the
real world through a technology called QuickTime Virtual
Reality (VR).
Move in any direction
When the cursor looks like this target, you
can hold down the mouse button and drag it to
move in any direction. This is the default cursor.
There are two ways to navigate around the ship. First, you
can walk around the ship by moving your cursor with the
mouse. Although you can open doors and walk up stairs,
you cannot walk through objects — you must move
around them. Second, you can click on the floor plan
hotspots which bring you directly to a designated location.
The ships in the Glomar fleet are also equipped with the
latest research instruments, such as the Data Center and
Instructional Terminals. These devices, as well as many
others like the television set and library books, are
activated by clicking on them once.
As students move the cursor over the ship image, the cursor
icon will change. The location of the cursor on each ship
image determines the icon at any given moment. The default
cursor, for instance, looks like a circle, but as soon as it
passes over an interactive instrument, like the Data Center
or a television, it turns into a hand. Here is a list of cursor
icons and what they do. Try them out yourself before you
introduce Ocean Expeditions: El Niño to your students.
Step forward
When the cursor becomes this arrow, click
the mouse button to move one step forward
at a time.
Turn around 360°
When you want to turn around, press and
hold down the mouse button, until you see
the cursor look like this. Then, drag the mouse
in the direction you want to turn.
Zoom in
To zoom in, press and hold the option key.
The cursor will change to look like this, and
the image will enlarge.
Zoom out
To zoom out, press and hold the control key.
The cursor will change to look like this, and
the image will reduce in size.
Hotspots
When the cursor changes to this hand
icon, the cursor is at a clickable hotspot,
such as a terminal. Click once to access the
object you are touching, for instance, to open
a door, or to move up or down stairs.
Using the Software
11
Using Floor Plan Hotspots
Saving and Quitting
Located directly below the QTVR screen is a floor plan.
To move directly to a location on the ship, click that level
(i.e., Level I Stern, Level I Lab, Level II Library, and
Level III Bridge). To move around on that level, click the
color-coded circles on that floor plan itself. The key
to the color codes is directly above the floor plan. Your
location is represented on the floor plan by the bright
green dot.
To save or quit the program, simply press the esc key,
or press command Q on the Macintosh or control Q on
Windows. This screen will allow you to save or quit your
game. If, after saving, you are not ready to quit, select the
resume button. You can also adjust volume here.
Getting Help Within the Program
Help is available at all times aboard the ship. Help information is context sensitive to the particular device or
interface students are using. The help information available from the Data Center, for example, is different from the
help information available in the Communication Center.
Click the help button in the lower left corner of the screen.
LEVELISTERN
WALL TERMINAL
GALLE Y/ENGINE R OOM
LEVEL II LIBRARY
LEVEL I LAB
LEVEL III BRIDGE
XBTDEVICE
LEVEL I
LEVEL I
LAB
STERN
Screen shot of ship’s floor plan
12
Ocean Expeditions: El Niño
Understanding the
Ocean Expeditions Process
O
cean Expeditions: El Niño is an interactive,
virtual research experiment designed to teach your
students the fundamentals of the scientific method,
as they learn about Earth and its dynamic climate system.
Keep in mind that your students can use Ocean
Expeditions: El Niño on their own and at their own pace.
Although your students make decisions while conducting
their investigation, the mission itself is highly structured.
Advice and direction are provided by a variety of video,
audio, and text messages.
You will monitor your students’ progress by reviewing
and grading the message files that they must complete
during their mission investigation.
The Scenario
Ocean Expeditions: El Niño is a simulated research mission that resembles a real scientific investigation. The
adventure takes place early in the 21st century. Dr. Enso,
director of the Earth Monitoring Organization (EMO),
hires your students as crew members of the Glomar fleet.
The crew undertakes a critical mission about a predicted
El Niño event that may have disastrous effects for life and
economies around the world.
The goal of your students, therefore, is to follow the scientific method to accurately confirm or refute the existence of
an El Niño event. As your students conduct the investigation, Dr. Enso asks them to respond to a series of questions
pertaining to their progress and findings. You should note,
however, that each time your students run the Ocean
Expeditions: El Niño simulation, there is a 50-50 chance that
the El Niño event will be in existence. Consequently, their
responses will change on each new run of the simulation.
Your students launch Ocean Expeditions: El Niño to enter
their new, virtual world and undertake their investigation.
Along the journey, your students follow the process of scientific inquiry outlined in this section.
The principal characters participating in the mission investigation are:
• Your students, the crew of scientists.
• Dr. Enso, director of the Earth Monitoring
Organization and scientific director of the
expedition.
• The captain, operator of the ship.
Student Roles and Materials
There is a common role that all students have: Earth System
scientist. An Earth System scientist is a member of a team
of scientists who studies the interactions between the air,
sea, land, snow, ice, and ecological systems.
Assign students to teams, with each team composed of the
following experts:
•
Navigator: Master of modern nautical navigation,
the navigator plots the ship’s destination and
maintains an efficient course.
•
Communications Exper t: This expert is in
charge of all ship communications and e-mail messages, including mission tasks directed by Dr. Enso
and messages sent and received from other vessels.
•
Data Collector: This expert is master of the ship’s
Data Center and an expert mapmaker.
•
Data Analyst: This expert is master of the ship’s
Data Archive and interpreter of maps.
Note: For use with smaller groups or for individual learning, students may play more than one role.
Make sure that each student on a team has a booklet. The
booklets identify a division of labor among the team and
provide each student with a role to play.
Make sure that each team has a worksheet. The worksheets serve two purposes. First, they create a division of
labor among teams by assigning teams to different climate
variables. The climate variables include pressure, wind,
currents, and clouds/precipitation. Second, the worksheets
provide the students with an offline guide to follow along
their mission. For example, Dr. Enso may ask them to
answer a question for a specific part of their investigation.
As the students look for the answers, they may forget the
question. The worksheet provides the question in an
offline format with enough room for the students to jot
down their answer.
Note: Blackline masters are provided for easy duplication
of the student worksheets.
Understanding the Ocean Expeditions Process
The Classroom Process
Collect and Analyze Data
The simulation follows the process of scientific inquiry.
Here are the specific steps your students undertake, including booklet references and recommended time frames.
Student Booklets: pages 9–10
Recommended Time Frame: days 3–6
Get Started and Sign In
Student Booklets: pages 1–5
Recommended Time Frame: day 1
1. View a brief introduction about the climate system
and the El Niño phenomenon.
2. Get dropped off on the ship via helicopter at one
of several locations in the Pacific Ocean to begin
the mission.
3. Greet the ship’s captain, who directs the Navigator
to the bridge to get the ship underway.
4. Plot course and navigate the ship to a predetermined
destination.
5. Meet Dr. Enso, who explains the mission to
‘nowcast’ the state of the climate system and
determine whether an El Niño event is occurring.
6. Learn about the El Niño climate phenomenon and
its impacts using interactive books and TV in the
ship’s library.
7. Answer questions about the impacts of El Niño.
Observe the System and Establish
a Hypothesis
Student Booklets: pages 6–8
Recommended Time Frame: day 2
1. Learn about sea surface temperature (SST) patterns
using the Instructional Terminals.
2. Identify typical SST features and patterns.
3. Compile a map of present SST conditions using
satellite and other instrument data in the Data Center.
4. Learn about SST patterns in relation to El Niño
events.
5. Compare the present SST map to historical SST
maps in the Data Archive.
6. Learn how SST patterns change as the ocean and
atmosphere interact through the air-sea interface.
7. Submit a hypothesis on the state of the climate
system — whether or not an El Niño is occurring.
13
1. Each team is assigned one or more climate variables
to study and analyze (surface currents, pressure,
wind, and clouds/precipitation).
2. Learn about the patterns and features of the climate
variable under investigation and its relationship to the
climate system.
3. Collect data of the climate variable under investigation
using the Data Center and create a map of present
conditions.
4. Compare the present map to historical maps in the
Data Archive.
5. Submit answers to questions about the patterns and
features of the climate variable under investigation
and its relationship to the climate system.
6. Validate findings with other teams’ findings on other
climate variables.
Submit Conclusions
Student Booklets: page 11
Recommended Time Frame: day 6
1. Learn about the coupled ocean-atmosphere, which
illustrates how climate behaves as a constantly
interconnected and interactive system.
2. Each team reviews its hypothesis and findings for
its assigned climate variable.
3. Each team submits and substantiates its conclusions
on the state of the climate.
4. Receive final report about validity of hypothesis
on the state of the climate system.
14 Ocean Expeditions: El Niño
Managing the Classroom Experience
E
arth System Science education is essential if we
are to train and inspire a new generation of
researchers capable of visualizing and solving the
future global problems of our delicate and everchanging
planet. Teaching Earth System Science, however, presents
an instructional challenge because its goal is to provide
students with not only a broad knowledge of many traditional disciplines (e.g., geology, chemistry, oceanography) but also of their complex interconnections. This
challenge can be met by training teachers in Earth System
Science and by developing the appropriate instructional
tools and materials, such as Ocean Expeditions: El Niño,
that illustrate and teach how the Earth operates as a system.
Preparing Yourself
Understand that no scientist is an expert in all areas
of Earth System Science, so please do not expect to
become one either. Rather, your role in class is primarily
as a facilitator and role model in problem solving and
information gathering, and to help students in the process
of discovery.
Here are ways to prepare for your role:
• Use the Teacher’s Tour on the CD-ROM (provided
in electronic format). If you used the Easy Install
option, it is located in the Teacher Materials folder
on your hard disk.
• Read the Detailed Scientific Background section
of this Teacher’s Guide to learn more about the
fundamental scientific concepts in the program.
• Go through the program yourself.
• Understand the rubric for assessing student
responses described in this Teacher’s Guide.
Organizing Your Classroom
Ocean Expeditions: El Niño can be used by a single
student at a single machine, several students to a machine,
or by a classroom as a whole. We recommend at least two
students per computer. This facilitates student interaction,
an important component of this product. Whatever your
preference, use the chart below to help determine the optimal
classroom setup. There are several factors to take into
account, such as the number of students in your class,
available computers, and students that you would like to
have at each machine.
If you have many students and very few computers, here
are a few special ideas. Project one computer so that all
the students can see it, such as by using an LCD display,
then use Ocean Expeditions: El Niño as a lecture tool.
Run the program as you normally would for a single user,
randomly asking your students for help. Because Ocean
Expeditions: El Niño parallels the scientific process, you
can take time to lecture on the process, explaining why
and how scientists operate. Use all the tools that are available in the program to create a rich learning experience.
For example, at the Instructional Terminal, play the
movies on any given topic. Then, go to the Data Center
and Data Archive to show your students how scientists
collect and analyze data. As an alternative, you could
allow your students to use Ocean Expeditions: El Niño as
an afterschool enrichment activity.
Number of Students
1–4
Number of Computers
1
2
3
4
5
6
7
8
9
10
5–8
9–12 13–16 17–20 21–24 25–28 29–32 33–36 37–40
The medium grey blocks represent
the recommended classroom setup.
Under this scenario, you have at least
one computer for up to four students.
The light grey blocks represent some
creative planning on your part. Under
this scenario, you will have enough
computers for at least half of the class
to be playing at a computer at any given
time, with the maximum number of
four students to a machine. If this is the
case, we recommend rotating your
students on and off the computers, as
time permits. While your students are
offline, try to provide enrichment activities centered around the students’
research topic of the day.
Managing the Classroom Experience
Creating Student Groups
Ocean Expeditions: El Niño purposely exposes your students
to new information in a familiar setting: the scientific
process. How familiar your students are with the topics
that they will be exposed to will vary greatly. In any case,
try to organize the teams according to these rules of thumb
from popular research in collaborative learning:
• Always assign students to teams, rather than let
students choose teams themselves.
• Each team should be a microcosm of the entire
class, made up of high, average, and low performing
students of race, ethnicity, and gender. The average
performance level of each team should be about
equal. There are two reasons for this. Students with
different performance levels on a team can tutor
each other, and by providing balanced teams, no
single team has an academic advantage.
The Com Center for Communications Expert
Navigation for Navigator
15
Ocean Expeditions: El Niño is designed with both cooperative and collaborative learning in mind. It is designed
to be used with one computer and a whole class or many
computers in a classroom or lab, with up to 4 students at
each computer.
Within each team, each student plays a role (Navigator,
Data Analyst, Data Collector, and Communications
Expert). Playing a role provides an opportunity for students to experience individual responsibility in group
decision making. The entire team collaborates to submit
the final hypothesis.
When more than one team uses the program, each team
logs on as a crew assigned to investigate a different climate
variable. As the mission progresses, each team is challenged to cooperate with another team to further support
each team’s scientific findings. For example, the team
investigating wind could greatly benefit from the findings
of the team investigating pressure. This cooperation is fostered via e-mail in the Com Center.
Data Center for Data Collector
Data Archive for Data Analyst
16
Ocean Expeditions: El Niño
Assessing Student Performance
Content Objectives
In Ocean Expeditions: El Niño, your students’ mission
is to verify a predicted El Niño event by determining the
present state of the climate system. As they pursue the
process of scientific inquiry, students must learn about the
fundamental processes which regulate the climate system
and, in turn, influence the El Niño phenomenon. They also
learn about El Niño’s impact upon society and species of
plants and animals around the world. By the time students
have verified their hypothesis, they will have gained a
broad understanding of the climate system and will have
met the following objectives.
Sea Surface Temperature (SST) —
Objectives
• Provide an example of the importance of SST
patterns to climate.
• Interpret SST maps derived from satellite data.
Surface Wind — Objectives
• Provide an example which relates surface wind to
climate in the tropical Pacific.
• Determine how surface wind develops.
• Identify the pressure features that give rise to the
Trade Winds.
• Identify the relationship between surface wind speed
and surface pressure.
• Interpret maps of surface wind.
• Identify Trade Wind patterns across the Pacific
during non El Niño and El Niño conditions.
Clouds/Precipitation — Objectives
• Identify how cloud and rainfall patterns of the
tropical Pacific vary from year to year.
• Interpret precipitation index maps.
• Describe the elements that influence SST patterns.
• Identify the two main features of SST patterns in
the tropical Pacific.
• Identify changes in cloud and precipitation patterns
between non El Niño and El Niño conditions.
• Identify SST patterns across the Pacific during non
El Niño and El Niño conditions.
Assessment Rubric
• Describe how SST patterns are a result of and influence local interactions between the air and the sea.
As your students complete their mission in Ocean
Expeditions: El Niño, they must respond to a series of
questions sent to them by Dr. Enso at Earth Monitoring
Organization (EMO) headquarters. These questions are
sent for two reasons: (1) to direct your students in their
investigation, and (2) to provide you, the instructor, with
a means of monitoring your students’ progress and evaluating their understanding of the scientific concepts in
Ocean Expeditions: El Niño. These questions are included
both in the Wall Terminal under Mission Status and in the
Student Worksheet. The mission report is automatically
saved as the text file under the Crew Name on the hard
disk in the folder named Student Reports.
Currents — Objectives
• Identify an example of how currents affect humans.
• Define surface currents.
• Name the major surface currents in the Pacific.
• Identify the direction in which each of the major
currents in the tropical Pacific flows.
• Interpret maps of surface currents.
• Identify surface current patterns across the tropical
Pacific during non El Niño and El Niño conditions.
Surface Pressure — Objectives
• Identify how pressure systems influence regional
climates in the tropical Pacific.
• Interpret maps of surface pressure.
• Identify surface pressure patterns across the Pacific
during non El Niño and El Niño conditions.
Below we have listed the questions asked throughout the
simulation, along with the correct answers. We have also
given you a description of what constitutes an excellent, a
good, and a poor response. Keep in mind, however, that
many of the questions have two answers depending on which
condition (data set) of Ocean Expeditions: El Niño is activated at start-up, namely the non El Niño or El Niño condition.
Assessing Student Performance
17
Observing the System
QUESTION
ANSWER
Identify three
Economic: flooding, hurriimpacts of El Niño. canes, drought/fire, reduced
agricultural production.
EXCELLENT
Student identifies
three of the impacts
of El Niño.
GOOD
Student identifies
two impacts.
POOR
Student
identifies
less than
two impacts.
Biological (Marine Life):
coral reef destruction, sea lion
pups killed, fisheries displacement (particularly anchovies
and sardines), food chain
threatened, sea birds starved.
Biological (Land Effects):
agricultural production disrupted, increase in malaria
and cholera, increased rainfall
and droughts.
QUESTION
Identify the two
dominant sea
surface temperature (SST) features
and explain how
they evolve.
ANSWER
The two dominant sea surface
temperature features are the
cold tongue and the warm
pool. The cold tongue evolves
as a result of two processes:
1) the transport of cold water
from the deep ocean towards
the surface, and 2) the transport of cold water towards the
equator by the Peru Current.
The warm pool forms as:
1) surface waters in the western Pacific absorb solar energy
and 2) as surface waters
warmed by solar energy
are transported westward
by equatorial currents into
the warm pool region.
EXCELLENT
GOOD
Student describes
two mechanisms for
the formation of the
cold tongue and one
mechanism for the
formation of the
warm pool.
Student identifies the
cold tongue and the
warm pool as the two
dominant sea surface
temperature features
but not the evolution
of these features.
POOR
Student is
unable to
identify
dominant
sea surface
temperature
features.
18
Ocean Expeditions: El Niño
Observing the System, continued
QUESTION
Describe the
present sea surface
temperature pattern.
Do these conditions
more closely
resemble El Niño
or non El Niño
conditions for
this time of year?
ANSWER
EXCELLENT
GOOD
POOR
Non El Niño: Present sea
surface temperature patterns
show a strong cold tongue
that extends from the
coast of South America
along the equator well into
the central Pacific. The
warm pool region remains
confined to the western
equatorial Pacific. These
sea surface temperature
conditions resemble non
El Niño conditions.
Student correctly
describes the sea
surface temperature
variation across the
Pacific using the terms
“warm pool” and “cold
tongue.” Student also
associates these conditions with the correct
conditions.
Student correctly
describes the sea
surface temperature
variation across the
Pacific without using
the terms “warm
pool” and “cold
tongue.” Student
also associates these
conditions with the
correct conditions.
Student does
not describe
the temperature
variation across
the equatorial
Pacific.
EXCELLENT
GOOD
POOR
El Niño: Present sea surface
temperature patterns show
a weak cold tongue that
is confined to the eastern
equatorial Pacific. The warm
pool remains close to the
equator and extends from
the western Pacific well into
the central Pacific. These sea
surface temperature conditions
resemble El Niño conditions.
Establishing a Hypothesis
QUESTION
What is your
hypothesis?
ANSWER
Answer is subjective.
Example 1: An El Niño
is not occurring because
the warm pool remains
confined to the western
Pacific and the cold tongue
extends along the equator
into the central Pacific.
Example 2: An El Niño
is occurring because the
warm pool extends
eastward into the central
Pacific and the cold tongue
is not well-defined.
Hypothesis considers
the warm pool and
cold tongue regions.
Hypothesis considers
either the warm pool
or cold tongue
region, but not both.
Hypothesis
does not
consider either
the warm pool
or cold tongue
region.
Assessing Student Performance
19
Surface Currents: Collecting and Analyzing Data
QUESTION
Describe the general
direction of the South
Equatorial Current
and the Equatorial
Countercurrent in
the eastern Pacific.
ANSWER
EXCELLENT
Non El Niño: In the
eastern Pacific, the South
Equatorial Current flows
from east to west. The
Equatorial Countercurrent
is not observed in the
eastern Pacific on the
surface current map.
Student correctly
identifies the direction
of the South Equatorial
Current and correctly
references the
Equatorial
Countercurrent.
GOOD
Student correctly
identifies the
direction of the South
Equatorial Current
but does not reference
the absence/presence
of the Equatorial
Countercurrent.
POOR
The direction
of the South
Equatorial
Current is
not identified
correctly.
El Niño: In the eastern
Pacific, the South
Equatorial Current flows
from east to west and the
Equatorial Countercurrent
flows from west to east.
QUESTION
Are these patterns
more consistent with
non El Niño or El
Niño conditions?
ANSWER
Non El Niño: The current
patterns are more consistent
with non El Niño conditions because the South
Equatorial Current is the
dominant current in the
eastern Pacific.
El Niño: The current
patterns are more consistent
with El Niño conditions
because the Equatorial
Countercurrent intensifies
in the eastern Pacific and
the South Equatorial
Current weakens in the
eastern Pacific.
EXCELLENT
Current patterns are
correctly identified as
being more consistent
with non El Niño/El
Niño conditions.
GOOD
POOR
Current patterns
are incorrectly
identified as
being more
consistent with
non El Niño/El
Niño conditions.
20
Ocean Expeditions: El Niño
Surface Currents: Collecting and Analyzing Data, continued
QUESTION
Are your surface
currents data consistent with the wind
data? Why?
ANSWER
Non El Niño: Yes they are
because both data sets reflect
non El Niño conditions. The
surface current data show that
the South Equatorial Current
is dominant in the eastern
Pacific and the wind data
show easterly winds are dominant in the western Pacific.
EXCELLENT
Student correctly
states that the two
data sets are
consistent and
explains why.
GOOD
Student correctly
states that the two
data sets are consistent but does not
explain why.
POOR
Student does not
state that the two
data sets are
consistent.
El Niño: Yes they are because
both data sets reflect El Niño
conditions. The surface current
data show an intensification of
the Equatorial Countercurrent
in the eastern Pacific and the
wind data show westerly
winds in the western Pacific.
Surface Pressure: Collecting and Analyzing Data
QUESTION
Describe the location and extent of
the high and low
regions in the
present surface
pressure fields.
ANSWER
Non El Niño: The region of
lowest surface pressure is
centered around the equator
in the western Pacific. Moving
eastward across the equatorial
Pacific, the pressure increases
but remains lower than the
pressure in the subtropical
and mid-latitudes.
EXCELLENT
Student describes the
pressure gradient that
exists across the
equatorial Pacific
and describes the
variation in pressure
as a small variation.
GOOD
Student identifies the
surface pressure as
being lower in the
western equatorial
Pacific and higher in
the eastern equatorial
Pacific but does not
qualify the variation.
POOR
Student does
not identify a
pressure gradient
across the equatorial Pacific.
El Niño: The region of lowest
surface pressure is centered
around the equator and extends
from the western into the
central Pacific. Traveling
further eastward, the surface
pressure increases slightly.
QUESTION
Do these pressure
features more closely
resemble non El
Niño or El Niño
conditions?
ANSWER
Non El Niño: Present pressure
conditions more closely
resemble non El Niño conditions. El Niño: Present pressure conditions more closely
resemble El Niño conditions.
EXCELLENT
Pressure pattern is
correctly identified
as resembling the
non El Niño/El Niño
conditions.
GOOD
POOR
Pressure pattern
is incorrectly
identified as
resembling the
non El Niño/El
Niño conditions.
Assessing Student Performance
21
Surface Pressure: Collecting and Analyzing Data, continued
QUESTION
Are your data on
pressure consistent
with the clouds/
precipitation data?
Why?
ANSWER
Non El Niño: Yes they are
because both data sets reflect
non El Niño conditions. The
pressure data show that the
region of lowest surface
pressure is confined to the
western tropical Pacific. The
clouds/precipitation data
show that the highest values
of the precipitation index
occur in the same region.
EXCELLENT
Student correctly
states that the two
data sets are consistent
and explains why.
GOOD
Student correctly
states that the two
data sets are
consistent but does
not explain why.
POOR
Student does
not state that
the two data sets
are consistent.
El Niño: Yes they are
because both data sets
reflect El Niño conditions.
The pressure data shows an
extension of the region of
lowest surface pressure into
the central Pacific and the
clouds/precipitation data
show increased rainfall
in the central Pacific.
Surface Wind: Collecting and Analyzing Data
QUESTION
Describe the general
direction of the
winds in the western
Pacific between
150° E–170° W.
QUESTION
How do the present
surface wind patterns
in this region compare to El Niño
and non El Niño
conditions?
ANSWER
Non El Niño: In the western
equatorial Pacific, the general
wind direction is from east
to west between 150° E
–170° W. El Niño: In the
western equatorial Pacific,
general wind direction is
from west to east between
150° E–170° W.
ANSWER
Non El Niño: They are
comparable to non El Niño
conditions because the general wind direction in the
western Pacific is from the
east to the west.
El Niño: They are comparable
to El Niño conditions
because the general wind
direction in the western Pacific
is from the west to the east.
EXCELLENT
GOOD
Student incorrectly
identifies the wind
direction.
Student correctly
identifies the wind
direction.
EXCELLENT
Present wind
conditions are
correctly identified
as resembling the
non El Niño/El
Niño conditions.
POOR
GOOD
POOR
Present wind
conditions are
incorrectly identified as resembling
non El Niño/El
Niño conditions.
22
Ocean Expeditions: El Niño
Surface Wind: Collecting and Analyzing Data, continued
QUESTION
Are your surface
wind data consistent
with the pressure
data? Why?
ANSWER
Non El Niño: Yes they are
because both data sets reflect
non El Niño conditions. The
surface wind data show easterly
winds in the western tropical
Pacific. The pressure data show
that the region of lowest surface
pressure is confined to the western tropical Pacific. El Niño: Yes
they are because both data sets
reflect El Niño conditions. The
surface wind data show westerly
winds in the western Pacific. The
pressure data show an extension
of the region of lowest surface
pressure into the central Pacific.
EXCELLENT
Student correctly
states that the
two data sets are
consistent and
explains why.
GOOD
Student correctly
states that the two
data sets are consistent but does not
explain why.
POOR
Student does not
state that the two
data sets are
consistent.
Clouds/Precipitation: Collecting and Analyzing Data
QUESTION
Describe the
overall precipitation
patterns of the
tropical Pacific.
QUESTION
How do the present
patterns compare to
El Niño and non El
Niño conditions?
ANSWER
Non El Niño: The most abundant precipitation occurs in
the western tropical Pacific.
Moderate precipitation occurs
in the central tropical Pacific and
little or no rainfall occurs in the
eastern tropical Pacific. El Niño:
The most abundant precipitation
occurs in the western and central
tropical Pacific. Moderate precipitation occurs in the eastern
tropical Pacific.
ANSWER
Non El Niño: They are comparable to non El Niño conditions
because the most abundant
precipitation is confined to
the western Pacific, moderate
amounts of precipitation are
found in the central Pacific,
and little or no rainfall is
found in the eastern Pacific.
El Niño: They are comparable
to El Niño conditions because
the most abundant precipitation extends from the western
Pacific into the central Pacific.
EXCELLENT
Student correctly
identifies the
precipitation
characteristics for
the western, central,
and eastern Pacific.
EXCELLENT
Present precipitation
patterns are correctly
identified as resembling the non El Niño/
El Niño conditions.
GOOD
Student identifies the
precipitation characteristics for only two
of the three regions
of the Pacific.
GOOD
POOR
Student is not
able to correctly
interpret precipitation index map.
POOR
Present precipitation patterns
are incorrectly
identified as
resembling the
non El Niño/El
Niño conditions.
Assessing Student Performance
23
Clouds/Precipitation: Collecting and Analyzing Data, continued
QUESTION
Are your precipitation index data
consistent with the
currents data? Why?
ANSWER
Non El Niño: They are
consistent with currents
data because both conditions
reflect non El Niño conditions.
Surface current data show
that the South Equatorial
Current is dominant in the
eastern Pacific and precipitation
index data show the most
abundant rainfall occurs
in the western Pacific.
EXCELLENT
GOOD
Student correctly
states that the two
data sets are consistent and explains why.
Student correctly
states that the two
data sets are consistent but does not
explain why.
EXCELLENT
GOOD
POOR
Student does
not state that
the two data sets
are consistent.
El Niño: They are consistent
with currents data because
both conditions reflect El
Niño conditions. Surface
current data show an intensification of the Equatorial
Countercurrent in the eastern
Pacific and the precipitation
index data show increased
rainfall in the central Pacific.
Submitting Your Conclusions
QUESTION
What is the present
state of the climate
system?
QUESTION
What evidence
do you have to
support your
claim?
QUESTION
Does the claim
support or refute
your hypothesis?
ANSWER
Answer is subjective.
ANSWER
Answer is subjective.
ANSWER
Answer is subjective.
Student correctly
identifies the state of
the climate system.
EXCELLENT
Student is able to
synthesize data for
at least two climate
variables and correctly relate the present
conditions for these
climate variables to
his/her hypothesis.
EXCELLENT
Student correctly
states that the data
collected supports/
refutes his/her
hypothesis.
POOR
Student incorrectly
identifies the state of
the climate system.
GOOD
POOR
Student is able to
synthesize data for
one climate variable and correctly
relate the present
condition of this
climate variable to
his/her hypothesis.
Student is not able
to relate data for
any of the climate
variables to his/
her hypothesis.
GOOD
POOR
Student incorrectly
states that the
data collected
supports/refutes
his/her hypothesis.
24
Ocean Expeditions: El Niño
Suggestions to Fit Your Curriculum
W
hat kind of science classes do you teach?
Earth science? Physical science? Chemistry?
The content and approach of Ocean
Expeditions: El Niño make it a valuable tool for students in
these classes and many more. Ocean Expeditions: El Niño
provides your students with a new approach to investigating
the Earth system and how it operates. Starting below we
provide you with three different examples of how you might
integrate Ocean Expeditions: El Niño into your curriculum.
Option I: Thematic Approach
Ocean Expeditions: El Niño follows a thematic approach.
Three basic themes have been used to develop this simulation.
Theme A: System and Interactions
A system is an interacting or interdependent group of
components that forms a unified whole. The components
are synergistic. Feedback is an important aspect of the
interaction between components and is the source of nonlinear variability of a system. A systems approach to Earth
science enables students to grasp some of the complexities
inherent to interactive components.
Earth is a complex system composed of the atmosphere,
hydrosphere, cryosphere, lithosphere and biosphere. These
components interact through exchange of: (1) matter, such
as nutrient cycles and erosion; (2) energy, such as absorption of solar radiation and release of latent heat; and (3)
momentum, such as winds that create ocean currents.
Ocean Expeditions: El Niño allows students to define the
boundaries of the ocean-atmosphere system, and then to
explore the system with its components, their interactions,
and their coupling.
Theme B: Patterns of Change
Patterns of change address the concepts of change,
dynamic stability, and predictability.
Ocean Expeditions: El Niño addresses patterns of change
directly by presenting Earth as a dynamic system undergoing constant change yet remaining in a state of dynamic
equilibrium with the universe. Regular cyclical, as well as
irregular non-cyclical, changes occur within the Earth
system. For example, seasonal cycles, light and dark
cycles, and the tides are regular and predictable patterns of
change. El Niño, on the other hand, is a non-cyclical event
that occurs every two to seven years. The intensity of an El
Niño event depends on interactions between the ocean and
the atmosphere, which itself displays considerable variability over the course of a year, as well as from year to
year. Predictions are more complex in a system with these
kinds of irregular changes, but new numerical prediction
models address these situations by including the major
non-linear processes that give rise to El Niño.
Theme C: Scale and Structure
Every system includes many different structures whose
properties and relationships can be examined at different
scales. Processes occurring at small scales eventually
impact processes at much larger scales, and vice versa.
With Ocean Expeditions: El Niño, students examine a
system at different scales to gain an understanding of the
importance scale has on their perception of structure. For
example, interactions within the Earth system range from
molecular to large-scale general circulation patterns.
Processes at different scales affect the evolution of the
atmosphere-ocean system during an El Niño. Surface evaporation introduces water vapor in the lower atmosphere
through microphysical processes. The water vapor later
condenses into cloud droplets in regions of ascending
motion. The process of droplet condensation heats the
atmosphere, thereby generating local atmospheric circulation and cooling the ocean surface. As clouds grow, they
act collaboratively to force larger-scale atmospheric circulations which, in turn, affect surface winds and pressure
patterns, driving ocean currents and ocean heat redistribution.
Suggestions to Fit Your Curriculum
Option II: National Standards
If your course does not follow a thematic approach, you
can use Ocean Expeditions: El Niño to meet the National
Science Education Standards set forth by the National
Academy of Sciences. Below are those standards that are
met by Ocean Expeditions: El Niño.
Content Standard A: Science as Inquiry
25
Content Standard D: Earth and Space Science
• Energy in the Earth system.
Content Standard E: Science and Technology
• Recognize abilities of technological design.
• Identify a problem or design a solution.
• Propose designs and choose between alternative
solutions.
• Identify questions and concepts that guide scientific
investigation.
• Implement a proposed solution.
• Design and conduct scientific investigations.
• Evaluate the solution and its consequences.
• Use technology and mathematics to improve
investigations and communications.
• Communicate the problem, process, and solution.
• Formulate and revise scientific explanations and
models using logic and evidence.
Content Standard F: Science in Personal and
Social Perspectives
• Environmental quality.
• Recognize and analyze alternative explanations
and models.
• Communicate and defend a scientific argument.
Content Standard B: Physical Science
• Motions and forces.
• Interactions of energy and matter.
Content Standard C: Life Science
• The interdependence of organisms.
• Matter, energy, and organization in living systems.
• The behavior of organisms.
Option III: State Frameworks
We designed Ocean Expeditions: El Niño to meet many of
the major state science frameworks in addition to the
National Science Education Standards. The California
State Science Framework was chosen as a model for these
standards, based upon California’s long-standing support
for education reform. Your state’s science framework is
probably very similar.
The main components of the California State Science
Framework that relate to Ocean Expeditions: El Niño are
reviewed on the next page.
26
Ocean Expeditions: El Niño
Science Framework for
California Public Schools
Physical Sciences
Section A: Matter
A3: What principles govern the interactions of matter?
How does the chemical structure determine the
physical properties of matter?
Section B: Reactions and Interactions
B2: What controls how substances change?
Section C: Force and Motion
C1: What is motion? What are the basic kinds of motion?
How is motion described?
C2: What is force? What are the characteristics of forces?
What is the relationship of force to motion?
Section D: Energy: Sources & Transformations
D1: What is energy? What are its characteristics?
D2: What do we do with energy? What changes occur
as we use it?
Section E: Energy: Heat
E1: What is heat energy? Where does it come from, and
what are its properties?
Section C: Oceanography
C1: How does the water cycle affect the climate, weather,
and life of the Earth? How does water affect surface
features of the land and the ocean floor?
C2: How do the oceans support life, and how have the
oceans and their marine life changed through time?
What are the oceans?
C3: How do waters circulate in the ocean, and how does
this circulation affect weather and climate?
C4: How do humans interact with the oceans? What may
be some long-term effects of human interactions with
the oceanic environments?
Section D: Meteorology
D1: What are the physical bases of the Earth’s climate
and weather?
D2: What are the major phenomena of climate and
weather? What are some of the large- and small-scale
causes of climate and weather?
D3: How are we affected by weather? How can we alter it?
Life Sciences
Section G: Energy: Light
G1: How does light enable us to see? What are the sources
of light? What is light?
Section A: Living Things
A4: How do humans interact with living things?
G2: What are the properties of light?
Section C: Ecosystems
C3: How do ecosystems change?
Earth Sciences
C4: What are the responsibilities of humans toward
ecosystems?
Section B: Geology & Natural Resources
B4: What are the responsibilities of humans toward
natural resources?
Detailed Scientific Background
27
Detailed Scientific Background
Introduction to Earth System
Science and Global Change
The results of modern scientific research have changed the
way we think about our planet Earth. For centuries, scientists had divided the study of Earth into specialized areas:
biologists investigated life, meteorologists studied the
atmosphere, oceanographers did research on the sea, and
other specialists were concerned with ice and snow or
land. Scientists working in each specialty often knew little
about the others. Each field developed its own jargon,
making communication across disciplines difficult.
The natural world, however, is not divided into separate
and independent subjects like university departments.
Instead, there are connections everywhere. Over the last
few decades, scientists have developed new research
methods and entirely new fields of study to understand
these connections. Ecology, for example, is a science that
deals with the relationships between living organisms and
their environments. Ecology focuses on ecosystems, complexes of interdependent plants and animals, together with
their physical environment. A pond is one example of a
small ecosystem. The Earth, on the other hand, is the
largest ecosystem.
Earth System Science is a field of science that deals with
phenomena that involve interactions between components
that make up Earth: the air, the sea, the land, snow and ice,
and the world of living things. Viewing Earth as a system,
a collection of interrelated elements that form a collective
whole, is key to understanding many aspects of change on
planet Earth. Systems are dynamic, changing in response
to forces of many kinds, both inside and outside the system itself. Over billions of years, Earth has undergone
enormous changes. Some were caused by external forces
such as changes in the Sun and in Earth’s orbit around it.
Some involved events occurring within the Earth system
itself, such as the movement of continents and the eruptions of volcanoes.
The Earth also changes from day to day and from month
to month — changes on these time scales are apparent to
all of us. Every child experiences the difference between
night and day. People who live near the shore see the
changes in sea level caused by tides. The mighty rhythm
of the seasons governs the lives of farmers, as well as the
migrations of birds. The climate is another aspect of the
Earth system that affects us all. Floods and droughts,
summer heat waves and frigid winter blizzards, dust
storms in the desert and hurricanes in the tropics are all
powerful examples of how climate affects people, as well
as animals and plants. More subtle changes in Earth
system also affect life:
• The loss of ozone in the stratosphere, dramatized
by the Antarctic ozone hole, allows harmful ultraviolet
radiation from the sun to reach Earth’s surface, causing
skin cancers and other damage such as an increased
incidence of cataracts and a weakening of the immune
system in humans; reductions in leaf area, shoot length,
and photosynthesis rates in many plants; and damage
to plankton at the base of the marine food chain.
• An increase in the natural greenhouse effect,
caused by people adding carbon dioxide and other
gases to the atmosphere, gradually warms Earth,
resulting in rising sea levels and changes in storm
patterns.
• El Niño, a phenomenon arising from the interplay
between the atmosphere and ocean in the tropical
Pacific, causes severe droughts in Australia and
heavy losses in the fishing industry in Peru.
These changes in Earth involve interactions between the air,
sea, land, snow and ice, and the world of living things,
including ourselves. The key to understanding, and eventually
to predicting all these phenomena, is Earth System Science.
28
Ocean Expeditions: El Niño
Tropical Ocean-Atmosphere
System
We live on the surface of Earth where, to us, the atmosphere appears to extend to enormous heights above our
heads. Likewise, the ocean appears very deep. But these
impressions are due entirely to our own tiny size, compared with the size of Earth itself. In fact, the atmosphere
and the ocean are thin outer layers on the spherical Earth,
rather like the skin on an apple. One astronaut, contemplating Earth’s planetary wrapping of atmosphere from the
viewpoint of an orbiting space capsule, described the
atmosphere as “a fragile seam of dark blue light.”
Since about 70 percent of the Earth surface is covered by
ocean, most of the atmosphere lies over water, not land.
Scientists call the boundary between the atmosphere and
ocean the “air-sea interface.” This is not a static interface,
but an active one, continuously changing. The air and the
sea are each in constant motion. These motions range from
the great current systems of the sea, such as the Gulf
Stream, to the powerful global atmospheric wind systems,
such as the jet stream. The motions also include waves on
the ocean surface driven by wind and gigantic tropical
storms and hurricanes fueled by energy from the warm
oceans, which in turn have been heated by the strong rays
of the sun. As the moving ocean and the moving atmosphere rub up against one another, these two mighty elements of the Earth system influence each other continually through the exchange of water, heat, and momentum:
• The sea gives up water to the air through
evaporation. The atmosphere returns it to the
ocean through precipitation.
• Heat exchange occurs just as a warm bowl of
soup heats the air above it while the air gradually cools the soup. Whenever two substances
such as the atmosphere and the ocean are in
contact, heat flows from the warmer one to the
colder one, tending over time to equalize their
temperatures.
• The exchange of momentum is illustrated by
the whitecaps which occur when strong winds
whip the sea surface into a frenzy of wild waves.
The continual dialogue between air and sea, this exchange
of water, heat, and momentum across the air-sea interface,
makes the air and the sea two components of a system.
Scientists have learned that they cannot understand the
system by studying only the air without considering the
sea, or vice versa. Instead, they must direct their research
at the combined system of ocean, atmosphere, and the
interactions between them. Scientists have a name for this
system: the coupled ocean-atmosphere system.
El Niño
In the tropical Pacific, from Southeast Asia to the west
coast of South America, the interactions between the
atmosphere and ocean are particularly strong. The ocean is
especially sensitive to the wind, with currents quickly
responding to changes in wind speed and direction, while
the atmosphere is powerfully affected by sea surface temperature. The results are often dramatic. Fishermen of
Ecuador and Peru have long known that every few years,
ocean surface waters warm, while along the coast there are
unusually strong thunderstorms, heavy clouds, and rain.
These events are synchronized not only with each other,
but with the seasons — typically occurring around
Christmas time. The conditions last for a few months and
temporarily reduce the abundance of fish in the region.
The fishermen call the event “El Niño” (“The Child”)
referring to Jesus Christ and symbolizing the association
of the phenomenon with Christmas. Scientists distinguish
between typical conditions and the El Niño conditions,
technically called “warm events.” Under typical conditions (or non El Niño conditions as they are referred to in
Ocean Expeditions: El Niño), very warm ocean surface
waters occur only in the western Pacific, just off Southeast
Asia and north of Australia, giving rise to abundant
rainfall in that area. The thermocline is shallow in the
eastern Pacific and slopes downward to the west, becoming relatively deep in the western Pacific. Trade Winds
blow steadily from east to west, causing cool, nutrient-rich
waters to rise to the surface off western South America.
These waters sustain the fishing industry in Ecuador
and Peru.
Detailed Scientific Background
During warm El Niño events, all this changes. The warm
surface waters are now found in the central and sometimes
eastern Pacific off the coasts of Ecuador and Peru, and are
accompanied by thunderstorms, heavy clouds, and rain.
The east-west slope of the thermocline becomes less
steep. Trade Winds weaken and occasionally cease
altogether. When they cease, they are replaced by winds
blowing from the west. The fisheries off South America
can collapse, since warm water depleted of nutrients is
unable to sustain the abundant marine life found during
typical conditions.
Yet El Niño also affects countries far from the tropical
Pacific. It causes changes in the jet stream, as well as in
global pressure and wind patterns, leading to unusual
weather in many parts of the world. For example, western
Canadian winters may be less severe during some El
Niños, heavy rains may occur over the southern United
States, and severe droughts can devastate Australia.
Nowadays, scientists use the term El Niño to refer to the
strong warm events in which the regular seasonal cycle
appears to be powerfully amplified, with ocean warming
typically persisting into May or June. Yet no two El Niños
are alike. For example, there were seven distinct El Niño
events between 1961 and 1989, each with a different pattern of unusual ocean temperatures, rainfall, and other climate parameters. Thus, scientists speak of “interannual
variability,” referring to the sequence of El Niños alternating with typical conditions over the course of many years.
This interannual variability is superimposed on the ordinary seasonal cycle, or “annual variability.” Scientists use
the term “phases of the climate system” to denote the fact
that at any one time, the tropical Pacific may be either
experiencing a warm event, be in typical conditions, or be
in transition between the two.
Methodology of Science
The story of El Niño is an especially successful example of
Earth System Science. It is also typical in many ways of
how any science makes progress. Science is a process, carried out by people who agree on a few fundamental principles. For example, they agree that research results should
be reproducible so that one scientist’s laboratory experiment or theoretical calculation can be checked by another.
In the scientific process, there is a need for several types of
scientists, including the lone investigator doing “small science” and the team member involved in “big science.”
29
What led to the research that provides our current ability
to understand and predict El Niño events? The story of this
research offers a fascinating look at how science works.
One of the early pioneers in the field was a British scientist, Sir Gilbert Walker, who worked in India during the
1920s. Walker noticed, by carefully studying weather
records, that atmospheric pressures on the eastern and
western sides of the Pacific are related. When the barometer is high in the east, it is low in the west, and vice versa.
Walker called this seesaw in pressure the “Southern
Oscillation.” The term “southern” comes from the fact that
Walker used measurements from stations in the Pacific
Ocean south of the equator, so the phenomenon was
occurring in the southern tropics.
Predicting El Niño
Part of the difficulty in understanding and predicting
El Niño is simply the task of adequately observing a
phenomenon which extends over such a large region: the
entire tropical Pacific Ocean and the atmosphere above it.
Today, however, an expensive array of instrumentation is
in place, ranging from buoys in the ocean to satellites
orbiting above the atmosphere. These instruments
continuously monitor key parameters such as sea surface
temperature and sea level, together with patterns of
atmospheric surface pressure and surface winds. These
instruments were not in place in 1982–83. They are in
place today because we recognize their value in allowing
scientists to observe and predict El Niño events.
Peru, for example, experienced a 14% decrease in the
gross value of its agricultural sector as a result of El
Niño’s effect on the rainy season of 1982–83. Rainfall was
far above normal. By the 1986–87 El Niño, scientists were
able to predict the event, and agricultural planners planned
crops based on the forecast. They knew to increase production of rice, which thrives in wet weather, over cotton
which does better in dry weather. As a result, Peru
increased the value of its agricultural sector by 3%, in
spite of El Niño. Brazil and other countries have also benefited from El Niño predictions.
30
Ocean Expeditions: El Niño
Forecasts need not be perfect to be useful. Just as a gambling casino can become wealthy by having the odds only
slightly in its favor, so a nation’s agriculture can profit by
relying on climate forecasts that are only a little better
than chance. Today, research is underway in many countries to improve the observations and computer models
which make these forecasts possible. The 1991–95 El
Niño, an exceptionally long-lived event, provided a realtime laboratory for researchers to test their most recent theories, and to predict many aspects of this El Niño.
Scientific Concepts
This section provides you with a broader understanding of
the underlying science in Ocean Expeditions: El Niño, and
it should help you answer your students’ questions as they
work through the simulated experiment in class. In the following sections we review the most important scientific
topics included in Ocean Expeditions: El Niño, and we
highlight some of the more complex concepts that are not
directly addressed in the instructional modules, such as
satellite remote sensing.
There is a significant distinction in terminology and science that you should clarify to your class early in the
investigation. It is important to remember that the El Niño
phenomenon, while aperiodic in nature, is an unusual or
anomalous climate condition. We have chosen to use the
term non El Niño to refer to the “typical” climate conditions (and in a conscious attempt not to use the potentially misleading word “normal”). Be sure that your students
recognize this difference and that they do not mistake non
El Niño for something that is odd or irregular.
We made this decision to use the terms non El Niño (or typical) conditions and El Niño conditions because it is still not
altogether clear how atypical El Niño conditions may be
with respect to interannual variability. In view of the continued human production of carbon dioxide and other greenhouse gases into the atmosphere, and with the prospect of
global warming still looming on the horizon, there exists the
possibility that El Niños may become the more typical climate condition. In 1991, for instance, one of the first-ever El
Niño events was accurately predicted. Its mere occurrence
was not remarkable, but what became remarkable was that
its signature lingered in the tropical Pacific for nearly four
years thereafter, perplexing many researchers and illustrating that nothing in nature is quite “normal.”
While instructing your class as they explore the Ocean
Expeditions: El Niño investigation, keep in mind that it is
structured around a systems approach to learning about
Earth. We have designed the investigation so that we do
not overemphasize the importance of any one element or
process, such as sea surface temperature and solar radiation absorption, for instance. Rather, we illustrate the
interactions among all of them: sea surface temperature,
pressure, winds, currents, and precipitation. This approach
highlights the importance of the air-sea interface, the
dynamic boundary layer where these two media rub
against each other, allowing the elements to interact, and
its complex link to the coupled ocean-atmosphere system.
This link explains how interactions occurring at the air-sea
interface can produce alterations in weather in remote
regions of the world.
In the following content materials, the first four topics deal
with the air-sea interface, and the last four topics relate to
the coupled ocean-atmosphere system. These topics follow
the instructional movies. You can use some of this information to help you prepare and organize your classes.
Detailed Scientific Background
Sea Surface Temperature
For the Sea Surface Temperature instructional module
we developed the following five movies, which provide a
comprehensive overview of sea surface temperature:
• Introduction to Sea Surface Temperature —
Illustrates the importance of sea surface temperature
to climate and describes how to interpret sea surface
temperature maps derived from satellite data.
• Factors Affecting Sea Surface Temperature —
Identifies solar radiation and ocean currents as the
two main factors affecting sea surface temperature.
• Cold Tongue and Warm Pool — Identifies the two
dominant sea surface temperature features in the
tropical Pacific, the cold tongue and the warm pool.
• SST Patterns: non El Niño and El Niño —
Describes how sea surface temperature patterns
change between non El Niño and El Niño conditions.
• SST and the Air-Sea Interface — Describes
how sea surface temperature patterns are a result
of and influence the local interactions between the
atmosphere and ocean.
31
Ocean Surface Warming
Processes responsible for warming the ocean surface are
the absorption of solar radiation and longwave radiation. Ocean surface warming is determined primarily by
solar radiation absorption. The amount of radiation reaching the surface depends mainly upon solar radiation
intensity, daylight hours, and clouds.
Solar Radiation Intensity
The intensity of solar radiation reaching Earth’s surface
depends on the distance separating the sun and Earth and
the angle at which the sun’s radiation reaches the surface.
The difference between this incidence angle and the
vertical is called the sun-zenith angle. In the tropics, solar
radiation reaches the surface at small sun-zenith angles,
whereas at mid- and polar latitudes, solar radiation
reaches the surface at larger sun-zenith angles. The larger
the sun-zenith angle, the greater the area over which the
radiation is distributed, thereby decreasing its intensity. In
addition, solar radiation reaching Earth at large sun-zenith
angles must travel through more atmosphere than radiation reaching Earth at small angles. The greater the
distance traveled through the atmosphere, the more likely
the radiation will be absorbed or reflected, decreasing the
intensity reaching the surface (see SST Figure 1).
Sea Surface
The temperature of the ocean surface is regulated by
processes that warm and cool the surface. In the movie,
Factors Affecting Sea Surface Temperature, we identify
the two strongest processes: a) absorption of solar radiation
(warming) and b) ocean currents (warming and cooling).
Other factors regulating ocean surface temperature are surface evaporation (cooling), surface absorption
(warming) and emission (cooling) of longwave radiation, and sensible heat loss (cooling).
These factors can be partitioned into those which occur at
the air-sea interface and those which occur within the
ocean. The absorption and emission of radiation, evaporation, and sensible heat loss take place at (or near) the airsea interface and illustrate the importance of the
interactions between the ocean and atmosphere to climate.
The warming and cooling effects of ocean currents take
place within the ocean.
SST Figure 1: Solar radiation striking Earth at large sun
zenith angles travels a longer path in the atmosphere than
radiation striking Earth at small sun-zenith angles, providing a greater opportunity for interaction with the
atmosphere.
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Ocean Expeditions: El Niño
As Earth rotates around the sun, the distance between
them varies. The amount of solar radiation reaching the
top of Earth’s atmosphere is greatest when the distance
separating the two is smallest. This occurs during the
Northern Hemisphere winter (Southern Hemisphere
summer). The least amount of solar radiation reaching the
top of the atmosphere occurs during the Northern
Hemisphere summer (Southern Hemisphere winter). This
is an important point to illustrate as students often mistakenly identify the winter months as the time of year when
the distance separating Earth and the sun is the greatest.
Daylight Hours
Over the course of a year, the number of daylight hours in
the tropical regions remains fairly constant at 12 hours per
day, providing a consistent supply of solar energy for heating the Earth’s surface. At higher latitudes, the number of
daylight hours varies with season, being smaller in winter
and greater in summer. At the poles, the number of daylight hours reaches 24 in the summer and decreases to zero
in the winter.
Clouds
Not all of the radiation entering the top of Earth’s atmosphere reaches the surface, due largely to the presence of
clouds. Clouds reflect incident solar radiation back
towards space. SST Figure 2 illustrates the relationship
between cloud type and reflectivity. Thick cumulus clouds
with extended vertical development are highly reflective
and reflect approximately 80% of incident solar radiation,
whereas cumulus clouds with less vertical development
reflect only 20%–50%. Clouds also absorb approximately
20% of the solar radiation impinging upon them, preventing it from reaching the surface.
Longwave Radiation Absorption
Unlike solar energy, which is absorbed only during
daylight hours, Earth’s surface continuously absorbs longwave radiation. Longwave radiation is emitted continuously by the atmosphere and clouds in all directions.
Radiation that is emitted towards the surface is absorbed
by Earth’s surface and warms it. Relative to solar radiation
absorption, longwave radiation absorption by the surface
plays a small warming role.
SST Figure 2: Thick cumulus clouds reflect approximately
80% of incident solar radiation, whereas less-developed
cumulus clouds reflect 20%–50% of incident solar radiation.
Ocean Surface Cooling
Processes responsible for cooling the ocean surface are
evaporation, longwave radiation emission, and sensible
heat loss.
Evaporation
Evaporation is the process whereby water molecules leave
the ocean surface, cooling it as energy is consumed in the
phase change from liquid water to water vapor. Only the
fastest moving water molecules evaporate from the
surface. Water molecules absorb energy until they attain
enough molecular motion to evaporate. The removal of the
fastest moving molecules from the ocean surface results in
a decrease of surface temperature, as temperature is a
measure of the average speed of the water molecules.
Evaporation is directly related to wind speed and temperature. As wind speed or temperature increases, evaporation
from the surface increases, which in turn increases the
ocean surface cooling.
In the tropical regions, evaporation is strong and plays a
larger role in regulating sea surface temperature than at
higher latitudes. In the western Pacific, the warm sea
surface induces a strong evaporation. In the eastern
Pacific, the evaporation is also high but is attributed
mainly to the strong and persistent Trade Winds.
Detailed Scientific Background
Longwave Radiation Emission
Earth’s surface continuously emits longwave radiation,
thereby cooling the surface. The amount of radiation
emitted by Earth’s surface is proportional to its temperature. In the tropics, the amount of cooling induced by
longwave radiation emission is generally small when
compared to that of evaporation. At higher latitudes, the
emission of longwave radiation can play a larger role
compared to surface evaporation.
Sensible Heat Loss
The loss of heat from the ocean to atmosphere through
conduction and convection is called sensible heat loss.
Conduction is heat transfer at the molecular level and
convection is heat transfer through mass movement.
Relative to surface evaporation and the emission of longwave radiation, sensible heat transfer plays a minor
cooling role.
Ocean Currents: Warming & Cooling
Ocean currents contribute to the warming and cooling of
the ocean surface by transporting water between regions
of different temperature. Surface currents warmed in tropical regions carry heat toward the pole while surface
currents cooled at high latitudes carry cold water toward
the equator. Additionally, vertical currents contribute to
the cooling of the ocean surface by carrying cold water
from the deep ocean towards the surface. This process is
known as upwelling and is discussed in more detail under
the heading Ocean Temperature: Upwelling below.
Satellite Measurements
of Sea Surface Temperature
The amount of longwave radiation emitted upward by the
ocean surface is a function of the sea surface temperature.
As emitted longwave radiation travels through the atmosphere, some of it is absorbed by atmospheric gases. Not all
longwave energy is absorbed by the atmosphere to the
same extent. In some longer wavelengths regions of the
electromagnetic spectrum, there is complete absorption
and little or no radiation reaches the top of the atmosphere.
In other regions, absorption by the atmosphere is minimal,
allowing most of the radiation emitted by the surface to
escape to space. These regions of the electromagnetic
spectrum are known as “atmospheric window” regions.
Measurements from satellite sensors taken in window
regions are used to determine sea surface temperature. The
33
actual determination of sea surface temperature is a
complicated process because the signal received at the
satellite is a combination of surface and atmospheric emission
and must therefore be separated into its component parts.
Under cloudy conditions, satellite determination of sea
surface temperature becomes further complicated. Clouds
interfere with the longwave radiation emitted by the
surface, even in the atmospheric windows, making satellite measurements of sea surface temperature difficult.
When cloud conditions exist, sea surface temperature
measurements from ships and buoys are used in combination with satellite observations to build complete coverage
maps of sea surface temperature. Satellite and surfacebased measurements, however, describe different properties of the ocean surface. Satellite observations describe
“skin” temperature, which is the temperature of the upper
few millimeters of the ocean from which radiation is emitted.
Measurements from ships and buoys, however, describe
the bulk temperature of the ocean, several meters below
the surface. At the surface, evaporative cooling lowers the
skin temperature relative to the bulk temperature by
approximately 0.5° C. When combining measurements of
bulk temperature with “skin” temperature, computer
models of the air-sea interface and upper ocean are used to
account for these differences.
Surface Currents
Four movies are included in the Surface Currents instructional module:
• Introduction to Surface Currents — Provides
an example of how ocean currents impact human
activities.
• Surface Currents — Provides a brief introduction
to the formation of ocean surface currents and identifies the major currents in the tropical Pacific.
• Current Maps — Describes how current maps
are developed and interpreted.
• Current Patterns: non El Niño and El Niño —
Identifies how current patterns change between
non El Niño and El Niño conditions.
34
Ocean Expeditions: El Niño
Below we provide a more in-depth look at: the formation
of currents by describing the relationship between the
Coriolis Force and ocean currents, and how current maps
are developed.
Formation of Ocean Surface Currents
In the instructional movie, Surface Currents, we provide
a brief introduction to the formation of surface currents by
identifying them as wind-driven. Another process, the
Coriolis Force, also plays a dominant role in the development of surface currents. The Coriolis Force is an
apparent force caused by the rotation of Earth. It explains
why the surface current direction differs from the overlying wind direction. As wind blows over the ocean
surface, momentum is transferred from the atmosphere to
the surface layers of the ocean, creating ocean surface
currents. The Coriolis Force acts upon the ocean surface
deflecting surface currents to the right of the prevailing
wind in the Northern Hemisphere, and to the left of the
prevailing wind in the Southern Hemisphere. Although
the Coriolis Force is nonexistent at the equator, it
increases with latitude and impacts surface currents as
close as 0.5° from the equator.
In the Pacific, the Trade Winds drive the North and South
Equatorial Currents. The North Equatorial Current flows
north of the equator in the latitude band between 10° to
25° N while the South Equatorial Current flows on both
sides of the equator from 3° N to 25° S. The South
Equatorial Current is generally stronger than the North
Equatorial Current because the southeast Trade Winds are
generally stronger than the northeast Trade Winds. As
they flow westward, these two currents become blocked
by land masses in the western Pacific causing water to be
deflected northward and southward into the Kuroshio and
East Australian Currents, respectively. Other water flows
back toward the central and eastern Pacific as the
Equatorial Countercurrent. Surface Currents Figure 1
illustrates the surface current system of the Pacific. The
formation of the Equatorial Countercurrent is described in
more detail under the heading Ocean Circulation:
Equatorial Countercurrent.
Surface Currents Figure 1: Surface currents of the Pacific.
Measuring Currents
Oceanographers rely on moored and drifting buoys to
obtain measurements of current speed and direction. As
part of the Tropical Ocean-Global Atmosphere (TOGA)
research campaign which extended from 1982–92, a large
network of moored buoys was established and a large
number of drifting buoys was deployed in the tropical
Pacific. One objective of TOGA was to study the coupling
between the ocean and atmosphere and it’s relationship to
the El Niño Southern Oscillation phenomenon.
Current meters attached to moored buoys provide currents
by measuring the speed and direction of water as it passes
the current meter (see Surface Currents Figure 2). Current
meters cannot be used to measure the current from ships
because it is not possible to hold ships stationary in the
open ocean. Drifting buoys measure currents by
measuring the displacement of a parcel of moving water.
After they are released into the open ocean, their position
over time is tracked by satellites.
Detailed Scientific Background
35
Here, we introduce: how surface pressure systems
develop, pressure gradients, and how surface pressure systems are maintained. We also discuss how to
interpret symbols which are unique to the maps in Ocean
Expeditions: El Niño.
Surface Pressure System Development
Surface air pressure is the pressure exerted by the weight
of the column of air above it. The weight of air is simply
the mass of air times gravity, where, for most purposes,
gravity is assumed constant. Average sea level pressure is
about 1 kilogram per square meter. This is equivalent to
1013 hecto-Pascals (hPa) or 1013 millibars (mb).
Historically, air pressure has been measured in units of
millibars. Recently, a new convention was implemented in
which air pressure is measured in units of hecto-Pascals.
Ocean Surface Currents Figure 2: Current meters
attached to moored buoys measure current speed and
direction at various depths in the ocean.
While TOGA implemented an extensive network of
moored and drifting buoys, limited time and space
samples leave gaps in maps of current fields. Complete
current fields are only obtained when measurements from
moored and drifting buoys are “assimilated” into
computer models of ocean circulation. The current fields
shown in the Data Archive and the instructional modules
are “assimilated” current fields developed from computer
models and actual measurements.
Surface Pressure
The instructional module Surface Pressure includes
three instructional movies:
• Introduction to Surface Pressure — Describes
how surface pressure systems influence regional
climates in the tropical Pacific.
• Surface Pressure Maps — Describes how surface
pressure maps are developed and interpreted.
• Surface Pressure Patterns: non El Niño and El
Niño — Describes how surface pressure patterns in
the tropical Pacific vary between non El Niño and
El Niño conditions.
Surface pressure systems develop as the mass of the
atmospheric column changes. Changes in the mass of an
air column are initiated by: changes in density and
changes in volume, that is, the number of molecules
occupying the air column.
Changes in Density
The density of a given volume of air depends on its
temperature and the type of molecules comprising it. As
air temperature increases, it expands, causing fewer air
molecules to occupy the original volume, thereby
decreasing its density. A given volume of air can be partitioned into dry air and moist air, with moist air being
lighter than dry air. As the ratio of moist air molecules to
dry air molecules increases, the density of a given volume
of air decreases.
The air in the eastern tropical Pacific is denser than the air
in the western tropical Pacific. In the eastern tropical
Pacific, the air above the ocean surface is relatively cool
and dry. The low temperature of the cold tongue region
keeps the air above it cool. The Trade Winds keep the air
relatively dry by transporting water vapor away from this
region as it evaporates off the ocean surface. In the
western tropical Pacific, the air above the surface is warm
and moist. The high surface temperature warms the air
above. The high temperature also moistens the air above
as water evaporates from the surface of the ocean. The
Trade Winds contribute to the moist conditions found
in the western Pacific. As they blow westward across the
36
Ocean Expeditions: El Niño
Pacific Ocean, the Trade Winds pick up moisture and
carry it towards the western tropical Pacific. In summary,
the warm, moist air of the western Pacific is less dense
than the cool, dry air found in the eastern Pacific.
Changes in Volume
The mass of an air column will change by increasing or
decreasing the number of air molecules comprising it,
while holding its temperature and ratio of moist air molecules to dry air molecules constant. Density increases as
air molecules enter an air column and decreases as
molecules leave an air column.
The number of air molecules in a column increases as air
masses converge towards the column. This occurs at the
surface in the western tropical Pacific, and in the upper
atmosphere in the eastern tropical Pacific. In the western
tropical Pacific, air converges towards the surface low
pressure system, while air in the upper atmosphere
accumulates over the surface high pressure region in the
eastern tropical Pacific.
Conversely, the number of air molecules in a column
decreases as air masses diverge away from the column. In
the eastern Pacific, this occurs at the surface as air masses
diverge away from the surface high pressure region. In the
western Pacific, this also occurs in the upper atmosphere
as air molecules move away from the surface low pressure
region. See Atmospheric Circulation: Walker Cell for
a more detailed description of convergence toward and
divergence away from an air column.
Pressure Gradient
A pressure gradient is a measure of the variation of pressure across a horizontal distance. An imbalance in pressure
creates a pressure gradient force which causes air to flow
from high to low pressure regions. This movement of air is
called wind. In the tropical Pacific, a pressure gradient
develops between the eastern and western Pacific as a
result of uneven heating in the atmosphere due to clouds.
When clouds form, water vapor condenses in the
atmosphere, releasing latent heat and thereby warming
the atmosphere. In the equatorial Pacific, uneven atmospheric heating between relatively clear regions in the
eastern Pacific and cloudy regions in the western Pacific
creates a pressure gradient in the lower atmosphere. The
western equatorial Pacific is characterized by towering
cumulonimbus clouds which extend vertically over
several kilometers. These clouds are often referred to as
“hot towers,” because they have a significant impact on
atmospheric heating. In contrast, the eastern equatorial
Pacific is dotted by small fair-weather cumulus clouds.
These clouds have limited vertical development and
thereby have a negligible impact on atmospheric heating.
Pressure System Maintenance
Temperature and moisture gradients play an important
role in the development of surface pressure gradients
between the eastern and western Pacific. In order to maintain these pressure features, another process must be
acting, otherwise the flow of air between the different
pressure regions will act to balance the horizontal pressure
gradient by decreasing pressure in high pressure regions
and increasing pressure in low pressure regions. Surface
pressure systems are maintained by adding or removing
mass (molecules of air) from the air column.
A surface low pressure region is maintained when there is a
net loss of mass from the air column. At the surface, wind
flows into regions of low pressure, thereby increasing the
mass of the air column. At the top of the air column above
a surface low pressure region, loss of mass results as air
diverges away from the column. When the loss of air mass
at the top of the column exceeds gain of mass at the
surface, a surface low pressure system is maintained.
A surface high pressure region is maintained when there is
a net gain of mass to the air column. The mass of the
column increases as air in the upper atmosphere converges
above a surface high pressure region. The mass of the
column decreases as surface wind flows away from
regions of high pressure. When the gain of mass at the top
of the column exceeds the loss of mass at the surface, a
surface high pressure system is maintained.
Surface Pressure Figure 1 illustrates how surface pressure
regions are maintained.
Detailed Scientific Background
37
Surface Wind
We include the following four instructional movies in the
Surface Wind module:
• Introduction to Surface Wind — Describes the
relationship between the Trade Winds and the
climate system in the tropical Pacific.
• Development of Surface Wind — Provides a
brief introduction to the development of surface
winds.
• Surface Wind Map — Describes how surface
wind maps are developed and how they are
interpreted.
Surface Pressure Figure 1: A surface low pressure is
maintained when divergence aloft is greater than surface
convergence. A surface high pressure region is maintained
when convergence aloft is greater than surface divergence.
Surface Pressure Map Interpretation
On maps of surface pressure, the letters “H” and “L” are
used to denote high and low pressure regions, respectively.
In the instructional modules for Ocean Expeditions: El
Niño, we use the letters “H, H” or “L, L” to denote regions
of relative pressure. That is, even in overall low pressure
regions, such as the tropics, we distinguish between lower
low pressure regions (“L”) and higher low pressure
regions (“L”) by using these relative symbols. Surface
Pressure Figure 2 illustrates how these symbols are used
on surface pressure maps.
Surface Pressure Figure 2: Surface pressure map showing regions of relative pressure.
• Surface Wind Patterns: Non El Niño and
El Niño — Illustrates how surface wind patterns
alter between non El Niño and El Niño conditions.
In this section, we: introduce the relationship between
the Coriolis Force and surface wind direction, identify
the Intertropical Convergence Zone and discuss how
wind measurements are obtained from satellites.
Surface Wind Development
Wind is the horizontal movement of air that results from
differences in horizontal air pressure and Earth’s rotation.
As a pressure gradient develops over a surface, wind flows
in the direction of the pressure gradient force, that is, from
high to low pressure, in an attempt to balance the pressure
difference. Because of Earth’s rotation, the Coriolis Force
causes wind to be deflected to the right of the pressure
gradient force in the Northern Hemisphere and to the left
of the pressure gradient force in the Southern Hemisphere.
As a result, wind spirals inward toward a region of low
pressure and spirals outward from a region of high pressure (Surface Wind Figure 1).
Surface Wind Figure 1: Arrows show wind spiraling
inward toward a low pressure region and outward from a
high pressure region.
38
Ocean Expeditions: El Niño
Intertropical Convergence Zone
In the tropical Pacific, the Trade Winds blow from the
northeast and southeast and converge just north of
the equator in a region known as the Intertropical
Convergence Zone (ITCZ). The ITCZ is a band of low
pressure around the equatorial regions and extends a few
hundred kilometers in the north-south direction. Because
only a weak pressure gradient exists within the ITCZ, the
ITCZ is characterized by light winds. These winds are
more commonly referred to as the Doldrums because of
the calm and humid conditions which prevail in the ITCZ.
The name “Doldrums” only partially describes wind conditions in the ITCZ. The ITCZ also experiences deep
storms and intense winds associated with “cloud clusters”
which are groups of deep cumulonimbus clouds clustered
together and easily seen on satellite images. See Clouds/
Precipitation: Clouds and Atmospheric Circulation
for a more detailed description of the cloud conditions
prevailing in the ITCZ.
Satellite Observations of Wind Speed
Satellites carry scatterometers which estimate surface
wind properties from space. Scatterometers are radars that
transmit short pulses of microwave energy to the surface.
They measure the intensity of the signal that returns to the
satellite after it backscatters, or reflects, off the ocean surface at a steep angle. The strength of the returned pulse
gives an indication of surface roughness. Surface roughness, in turn, provides information about wind properties.
Small, wind-driven waves (a few centimeters in height)
influence the amount of energy reflected back towards the
satellite. Wind speed and wind direction are then determined by studying the variation in the signal received at
the satellite.
Satellite technology is only now reaching the stage where
it is able to produce high-resolution wind fields. In Ocean
Expeditions: El Niño, the wind fields are compiled from
wind measurements from ships and moored buoys which
are assimilated into computer models of atmospheric
circulation.
Clouds/Precipitation
The coupled ocean-atmosphere system is the combined
system of the ocean and atmosphere and the interactions
between them. In the next four sections, we address several
components of the coupled ocean-atmosphere system,
namely, Clouds/Precipitation, Ocean Temperature,
Atmospheric Circulation, and Ocean Circulation. The
Clouds/Precipitation instructional module addresses the
following topics:
• Introduction to Clouds and Precipitation —
Describes how clouds and rainfall patterns in the
tropical Pacific vary between non El Niño and
El Niño conditions. It uses cloud type to describe
what changes occur.
• Precipitation Index Maps — Describes how
precipitation index maps are developed and how
to interpret precipitation index maps.
• Precipitation Patterns: Non El Niño and
El Niño — Describes how precipitation patterns
change between non El Niño and El Niño conditions;
uses maps of the precipitation index maps to
illustrate differences.
This section takes a more in-depth look at the relationship
between: clouds and atmospheric circulation, and
clouds and precipitation. We also discuss how satellites
are used to infer precipitation amounts.
Clouds and Atmospheric Circulation
A comparison of clouds and sea surface temperature patterns in the tropical Pacific shows that the most intense
clouds form over the warmest waters, while relatively
cloud-free regions occur over cooler water. Additionally,
fog tends to form over the coldest waters associated with
regions of upwelling. The warmest waters are located
in the western Pacific and extend eastward north of the
equator. This warm-water band coincides with the region
of lowest surface pressure, the ITCZ. The Trade Winds
transport moisture-laden air into the ITCZ, which supplies
the fuel necessary for the production of intense
cumulonimbus clouds.
Cumulonimbus clouds form as the moist air which
converges at the surface rises and condenses. As cumulonimbus clouds develop, they heat the atmosphere
Detailed Scientific Background
through the release of latent heat creating uneven heating
in the atmosphere between clear and cloudy regions. In the
Pacific, regions of uneven atmospheric heating exist in the
meridional direction between the ITCZ and the relatively
cloud-free regions of the subtropics and in the zonal direction between the eastern and western Pacific. This creates
surface pressure gradients which drive the Hadley and
Walker circulation cells. For a more complete description
see: Hadley Cell and Walker Cell under the heading
Atmospheric Circulation.
The ITCZ is characterized by towering cumulonimbus
clouds and heavy rainfall. As moist air converges into the
ITCZ, it is forced to rise. Moist, rising air encounters
lower temperatures causing its water vapor to condense,
producing cumulonimbus clouds. In the upper atmosphere, air diverges away from the ITCZ and starts to sink.
Sinking air, away from the convergence zone, limits the
upward vertical motion required for the production of
intense rain clouds keeping these regions relatively cloudand rain-free.
Along the equator, the eastern Pacific is characterized by
small puffy, or Trade Wind, cumulus clouds. Because of
their limited vertical development, these clouds produce
minimal rainfall. The central Pacific is characterized by
cumulus clouds with greater vertical development which
produce moderate amounts of rainfall. The western Pacific
is characterized by cumulonimbus clouds with extensive
vertical development. These clouds, which often develop
into thunderstorm clouds, reach from the surface through
the entire troposphere and produce the most abundant rainfall. Clouds/Precipitation Figure 1 illustrates the clouds and
precipitation patterns that exist across the tropical Pacific.
Clouds/Precipitation Figure 1: Clouds and precipitation
patterns of the tropical Pacific.
39
Precipitation Index Maps
Precipitation is estimated from satellite observations in the
form of a precipitation index, as most satellites do not
measure precipitation directly. From visible and infrared
measurements, estimates of precipitation are calculated
using varying formulas based on cloud type, cloud height,
cloud coverage, or rainfall potential. Measurements from
visible channels are used to estimate cloud type (or cloud
brightness) and cloud coverage, while measurements from
infrared channels are used to obtain cloud height. Ground
measurements of rainfall show that the brightest clouds
with the highest cloud tops produce the most rainfall.
Ocean Temperature
In Ocean Expeditions: El Niño, students become familiar
with how ocean temperature changes with depth by taking
measurements with an expendable bathythermograph
(XBT). In this section, we provide a more in-depth investigation by: identifying vertical temperature regions
found in the ocean, describing how the mixed layer
varies across the Pacific, and discussing the physical mechanisms of upwelling.
Vertical Temperature Variations
If the absorption of solar radiation were the only factor
responsible for heating the upper ocean, temperature would
decrease with depth linearly from the surface. Surface
winds, however, create stirring in the upper layer of the
ocean which causes warm surface waters to mix vertically
with colder, deeper waters. Vertical mixing is also induced
by convection associated with nighttime cooling.
The vertical distribution of temperature in the ocean can
be divided into three temperature regions: the mixed layer,
the thermocline, and the deep ocean water. The mixed
layer is the uppermost layer and is characterized by
uniform temperature. The thermocline is a region of rapid
temperature transition that separates the warmer upper
waters of the mixed layer from the colder waters of the
deep ocean.
40
Ocean Expeditions: El Niño
Mixed Layer/Thermocline
Surface winds and vertical ocean currents can have competing effects on the thickness of the mixed layer. Surface
winds impact the thickness of the mixed layer from above,
whereas vertical currents impact the thickness of the
mixed layer from below. Strong surface winds create
intense stirring in the upper ocean, favoring the formation
of a thick mixed layer. Weak winds, on the other hand,
limit vertical mixing, resulting in a shallow mixed layer.
Equatorial currents transport surface waters away from the
eastern Pacific. Vertical currents allow deeper and colder
waters to mix with warmer surface waters, replenishing
water transported away by surface currents. This process
is called upwelling and creates a fairly shallow mixed
layer of approximately 10–50 meters in the eastern
Pacific. In the western Pacific, warm water build up and
surface winds act together to create a thick mixed layer of
approximately 150 meters. Ocean Temperature Figure 1
illustrates how the zonal variation in the depth of the
mixed layer causes the thermocline to slope upwards from
the western to the eastern Pacific during non El Niño
events. During El Niño events, the thermocline slope flattens as the thickness of the mixed layer becomes more uniform across the Pacific as illustrated in Ocean
Temperature Figure 2. The weakened upwelling and intrusion of warm surface waters increase the thickness of the
mixed layer in the central and eastern Pacific.
Ocean Temperature Figure 2: Same as Ocean
Temperature Figure 1 except for El Niño conditions.
Upwelling
In Ocean Expeditions: El Niño, the concept of upwelling
is introduced in several of the instructional movies,
namely Air-Sea Interface, Coupled Ocean Atmosphere
and Factors Affecting Sea Surface Temperature.
Here we discuss the physics of upwelling and the impact
of upwelling in the eastern Pacific.
Upwelling is the process of vertically transporting deep
water towards the surface and is caused by the action of
the winds, currents, and Earth’s rotation. As surface winds
drive surface currents, Earth’s rotation deflects surface
waters to the right of their path in the Northern
Hemisphere and to the left of their path in the Southern
Hemisphere. In the Pacific, this causes surface waters to
move away from the coast of South America and away
from the equator, exposing the surface to colder, nutrientrich waters that are upwelled from the deep ocean.
When the Trade Winds relax, for example, during El Niño
events, upwelling weakens as weaker surface currents
transport less water away from the equator and the South
American coast. Under these conditions, upwelling is
suppressed, and deep ocean water is prevented from
reaching the surface.
Ocean Temperature Figure 1: Cross section of Pacific
Ocean temperature at the equator during non El Niño
conditions.
Detailed Scientific Background
Atmospheric Circulation
Ocean Expeditions: El Niño introduces atmospheric circulation in the Clouds/Precipitation instructional module
and the Coupled Ocean-Atmosphere instructional
movies. In this section, we examine the two large-scale
circulation cells in the tropical Pacific: the Hadley Cell
and the Walker Cell.
Hadley Cell
The meridional pressure gradient existing between the
tropical low pressure band, the ITCZ, and the subtropical
high pressure band in the northern and southern hemispheres contributes to the formation of a north-south
circulation cell, known as the Hadley Cell. Surface winds
converge in the ITCZ, where air is forced to rise. Air
continues to rise until it reaches the tropopause, a stable
region in the atmosphere. The tropopause acts as a lid,
preventing air from rising farther and causing it to flow
horizontally in either the north-south or east-west directions. Airflow aloft in the north-south direction becomes
part of the Hadley Cell and airflow in the east-west
direction becomes part of the Walker Cell. Atmospheric
Circulation Figure 1 illustrates the Hadley and Walker
Cells. Hadley Cell circulation is comprised of two meridional branches, the northern branch which extends from
the equatorial regions to the subtropical regions of the
Northern Hemisphere and the southern branch which
extends from the equatorial regions to the subtropical
regions of the Southern Hemisphere.
Atmospheric Circulation Figure 1: Hadley and Walker
Cell circulation patterns.
41
As air aloft travels to higher latitudes, it changes direction
and it cools. The Coriolis Force increases with increasing
latitude causing the direction of airflow aloft to gradually
change from poleward to eastward. Air cools as it travels
poleward because less heat is acquired than in the tropical
regions. Air density increases as the air cools, causing
it to sink. When the air reaches subtropical latitudes, it
descends towards the surface, creating a band of high
surface pressure. Surface winds flow toward the equator
from this surface high pressure region. In the Northern
Hemisphere, surface winds blow from the northeast, while
in the Southern Hemisphere, they blow from the southeast
and make up the northeasterly and northwesterly components of the Trade Winds.
Walker Cell
In addition to the meridional pressure gradient between
the subtropical and equatorial pressure regions, a zonal
pressure gradient exists along the equator. The towering
cumulonimbus clouds heat the atmosphere in the western
Pacific through the release of latent heat creating regions
of differential atmospheric heating between the western
and eastern Pacific and also between the western Pacific
and the western Indian Ocean. As a result, alternating
regions of high and low pressure are found along
the equator. Surface winds converge towards the low pressure regions of the western Pacific. There, air rises. At
the tropopause, air diverges and travels horizontally in
the east-west direction. It accumulates and sinks over the
surface high pressure regions in the eastern Pacific and
western Indian Oceans, giving rise to the Walker Cell. The
lower branch of the Walker Cell is the east-west component of the Trade Winds. This component of the wind is, in
general, larger than the north-south component discussed
above. During El Niño conditions, the entire Walker Cell
shifts eastward. In the Pacific, the ascending branch of the
Walker Cell is found in the central rather than western
Pacific while the descending branch is found over the
South American continent, rather than the eastern Pacific.
42
Ocean Expeditions: El Niño
Ocean Circulation
Ocean circulation is intimately related to the interactions
between the atmosphere and ocean and is critical to
understanding El Niño events. A complete introduction to
ocean circulation, however, lies beyond the scope of this
document. Ocean circulation is therefore only briefly
introduced in the instructional movie Coupled OceanAtmosphere. Here, we provide an overview of ocean circulation including: sea surface height, the Equatorial
Countercurrent, and the Equatorial Undercurrent.
We also discuss how each of these processes change as
the climate system shifts between non El Niño and
El Niño conditions.
gradient by another surface current, the Equatorial
Countercurrent. The Equatorial Countercurrent flows in
the region between 4 and 10 degrees North. The surface
winds are weak in this region, enabling the current to flow
in the direction opposite to the prevailing winds. During
El Niño events, the Equatorial Countercurrent intensifies
in response to the associated changes taking place at the
air-sea interface.
Sea Surface Height
In the equatorial Pacific, the North Equatorial and South
Equatorial Currents move water westward, away from the
coast of Central and South America. The flow of water
becomes blocked by land masses in the western Pacific,
causing water to pile up against Southeast Asia, northern
Australia, and Indonesia. The transport of water from the
eastern to the western Pacific creates a variation in sea
surface height of approximately 50 cm across the equatorial Pacific, with sea surface height sloping upwards
towards the west. On the eastern side of the Pacific, water
that has flowed westward is replaced by upwelling of
cold, deep, nutrient-rich water.
As El Niño conditions develop, weakened westwardflowing surface currents limit the pileup of water against
the western boundary of the Pacific. This decreases the
variation in sea surface height across the Pacific and flattens the slope of sea surface height. Ocean Circulation
Figure 1 illustrates how sea surface height varies between
non El Niño and El Niño conditions.
Equatorial Countercurrent
As water piles up against the western boundary of the
Pacific basin, some water is deflected into the Kuroshio
and East Australia Currents. Other water creates a return
flow back towards the eastern Pacific. Because the sea
surface slopes upward from the eastern to the western
Pacific, there is an eastward-directed horizontal pressure
gradient force acting upon the ocean surface. As with the
atmosphere, the ocean responds to pressure gradients with
the generation of currents which flow from high to low
pressure. The horizontal pressure gradient force causes
water to be transported in the direction of the pressure
Ocean Circulation Figure 1: Variation in sea surface
height between non El Niño and El Niño conditions.
Equatorial Undercurrent
The sea surface slopes upward towards the west, as water
builds up against the boundary of the western Pacific. The
water buildup also creates a horizontal pressure gradient
below the ocean surface, with pressure higher in the
west and lower in the east. This initiates the Equatorial
Undercurrent, also called Cromwell Current, which flows
in the direction of the pressure gradient. The Equatorial
Undercurrent flows in the thermocline, just below the
wind-driven surface currents.
During El Niño events, the flatter sea surface height
and thermocline slopes weaken the horizontal pressure
gradient across the Pacific, causing a weakening of the
Equatorial Undercurrent. During the intense 1982–83 El
Niño, the normally swift Equatorial Undercurrent just
about disappeared for a few months.
Appendix: Worksheet Masters
Appendix:
Worksheet Masters
43
Currents Worksheet
Start Here
page 1
after reading pages 3–4 in your booklet.
Surface Currents and the Tropical Pacific
urface currents are movements of water in the upper few tens of meters of the ocean. In Peru and
Ecuador, the local fishermen know from experience how important these currents are and how they can
change. When the Peru Current, which flows northward along the coast of South America, is strong, surface
water temperature drops, nutrients abound in the upper ocean, and the anchovy industry thrives. But when
the Peru Current weakens, warm waters invade the coastal regions, nutrient levels decrease, and the
anchovy industry declines. The connection between the Peruvian anchovy industry, sea surface temperature,
and local ocean currents is an example of how the interaction between the ocean and atmosphere
determine climate and affect people.
S
Sign In
after reading page 5 in your booklet.
Your Teammates:
Crew Name:
Your Name:
Your Role:
Climate Variable Under Investigation:
Observe the System
✔ Currents ❏ Pressure ❏ Wind ❏ Clouds/Precipitation
❏
after reading pages 6–8 in your booklet.
1. Identify three impacts of El Niño.
2. Identify the two dominant sea surface temperature (SST) features and explain how they evolve.
3. Describe the present sea surface temperature pattern.
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Currents Worksheet
Establish a Hypothesis
page 2
after reading page 8 in your booklet.
What is your hypothesis?
Collect and Analyze Data
after reading pages 9–10 in your booklet.
1. Follow these basic steps to complete your investigation on Currents. Then, answer the questions below.
Dr. Enso will give you all the detailed instructions you may need to complete your repor t.
• Use the Instructional Terminal to watch four movies about Currents:
Introduction: Describes an example of how ocean currents have an impact on human activities.
Surface Currents: Provides a brief introduction to the formation of ocean sur face currents.
Current Maps: Describes how sur face current maps are developed and how they are interpreted.
Current Patterns: Identifies how current patterns change between non El Niño and El Niño conditions.
• Use the Data Center to build a map of present sur face current conditions. Sources for sur face
current data include: buoys, ships of oppor tunity, island stations, and on board the ship. (Note:
No satellite data are available.)
• Use the Data Archive to analyze your sur face current map and compare it to historical maps.
• Confirm or refute your hypothesis with your team.
• Complete your repor t to Dr. Enso at the Com Center.
2. Describe the general direction of the South Equatorial Current and the Equatorial Countercurrent in the eastern Pacific.
3. Are these patterns more consistent with non El Niño or El Niño conditions?
4. If another ship in the fleet is studying wind, see if your surface current data are consistent with the wind data.
Why or why not?
Submit Your Conclusions
after reading page 11 in your booklet.
1. What is the present state of the climate system?
2. What evidence do you have to support your claim?
3. Does this claim support or refute your hypothesis?
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Pressure Worksheet
Start Here
page 1
after reading pages 3–4 in your booklet.
Pressure and the Tropical Pacific
n the tropical Pacific, semi-permanent pressure features cover large areas and play an important role in
determining regional climates. The small fair-weather cumulus clouds found in the eastern tropical Pacific
are typical of the high pressure system that persists in this region. Small amounts of rainfall occur there
because high pressure is accompanied by sinking air motions that prevent the formation of tall rainproducing clouds.
I
On the western side of the Pacific Ocean, climate conditions are dramatically different. There, low pressure
and rising air motions give rise to tall rain-producing clouds. These thunderstorm clouds produce much of
the abundant rainfall that characterizes the region. The links between surface pressure, clouds, and rainfall
are important components of the climate system. Scientists regularly monitor surface pressure, along with
other climate variables, in the tropics to help predict how climate will change.
Sign In
after reading page 5 in your booklet.
Your Teammates:
Crew Name:
Your Name:
Your Role:
Climate Variable Under Investigation:
Observe the System
✔ Pressure ❏ Wind ❏ Clouds/Precipitation
❏ Currents ❏
after reading pages 6–8 in your booklet.
1. Identify three impacts of El Niño.
2. Identify the two dominant sea surface temperature (SST) features and explain how they evolve.
3. Describe the present sea surface temperature pattern.
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Pressure Worksheet
Establish a Hypothesis
page 2
after reading page 8 in your booklet.
What is your hypothesis?
Collect and Analyze Data
after reading pages 9–10 in your booklet.
1. Follow these basic steps to complete your investigation on Pressure. Then, answer the questions below.
Dr. Enso will give you all the detailed instructions you may need to complete your repor t.
• Use the Instructional Terminal to watch three movies about Pressure:
Introduction: Describes how sur face pressure systems influence regional climates in the tropical Pacific.
Pressure Maps: Describes how sur face pressure maps are developed and how they are interpreted.
Pressure Patterns: Describes how sur face pressure patterns in the tropical Pacific var y between non
El Niño and El Niño conditions.
• Use the Data Center to build a map of present sur face pressure conditions. Sources for pressure
data include: buoys, ships of oppor tunity, the Glomar fleet, island stations, and on board the ship.
( Note: No satellite data are available.)
• Use the Data Archive to analyze your pressure map and compare it to historical maps.
• Confirm or refute your hypothesis with your team.
• Complete your repor t to Dr. Enso at the Com Center.
2. Describe the location and extent of the high and low regions in the present surface pressure fields.
3. Do these pressure features more closely resemble non El Niño or El Niño conditions?
4. If another ship in the fleet is studying clouds/precipitation, see if your data on pressure are consistent with
the clouds/precipitation data. Why or why not?
Submit Your Conclusions
after reading page 11 in your booklet.
1. What is the present state of the climate system?
2. What evidence do you have to support your claim?
3. Does this claim support or refute your hypothesis?
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Wind Worksheet
Start Here
page 1
after reading pages 3–4 in your booklet.
Surface Wind and the Tropical Pacific
n the tropical Pacific, the general wind direction is from the northeast in the Northern Hemisphere and from
the southeast in the Southern Hemisphere. These relatively steady winds are called the Trade Winds, named
because merchant sailing ships relied on them to trade between continents. These winds are also important
to the climate system. Under typically strong Trade Wind conditions, the eastern tropical Pacific enjoys fair
weather, while the western tropical Pacific experiences heavy rainfall. When the Trade Winds weaken, as during
an El Niño, climate conditions change. The central and eastern tropical Pacific receive substantial rainfall, while
a lack of rain, or even a drought, characterizes the western tropical Pacific. This link between the Trade Winds
and tropical rainfall is just one aspect of how the global climate system operates across vast distances.
I
Sign In
after reading page 5 in your booklet.
Your Teammates:
Crew Name:
Your Name:
Your Role:
Climate Variable Under Investigation:
Observe the System
✔ Wind ❏ Clouds/Precipitation
❏ Currents ❏ Pressure ❏
after reading pages 6–8 in your booklet.
1. Identify three impacts of El Niño.
2. Identify the two dominant sea surface temperature (SST) features and explain how they evolve.
3. Describe the present sea surface temperature pattern.
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Wind Worksheet
Establish a Hypothesis
page 2
after reading page 8 in your booklet.
What is your hypothesis?
Collect and Analyze Data
after reading pages 9–10 in your booklet.
1. Follow these basic steps to complete your investigation on Winds. Then, answer the questions below.
Dr. Enso will give you all the detailed instructions you may need to complete your repor t.
• Use the Instructional Terminal to watch four movies about Sur face Wind:
Introduction: Describes the relationship between Trade Winds and climate system in the tropical Pacific.
Development: Provides a brief introduction to the development of sur face winds.
Wind Maps: Describes how sur face wind maps are developed and how they are interpreted.
Wind Patterns: Illustrates how sur face wind patterns alter between non El Niño and El Niño conditions.
• Use the Data Center to build a map of present sur face wind conditions. Sources for wind data include:
satellite, buoys, ships of oppor tunity, the Glomar fleet, island stations, and on board the ship.
• Use the Data Archive to analyze your wind map and compare it to historical maps.
• Confirm or refute your hypothesis with your team.
• Complete your repor t to Dr. Enso at the Com Center.
2. Describe the general direction of the winds in the western Pacific between 150˚ E–170˚ W.
3. How do the present surface wind conditions in this region compare to El Niño and non El Niño conditions?
4. If another ship in the fleet is studying pressure, see if your surface wind data are consistent with the pressure data.
Why or why not?
Submit Your Conclusions
after reading page 11 in your booklet.
1. What is the present state of the climate system?
2. What evidence do you have to support your claim?
3. Does this claim support or refute your hypothesis?
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Clouds/Precipitation Worksheet
Start Here
page 1
after reading pages 3–4 in your booklet.
Clouds/Precipitation and the Tropical Pacific
n the 1930s, Sir Gilber t Walker obser ved that the wind and rainfall patterns of the tropical Pacific
can change considerably from year to year. Most years, the western tropical Pacific receives abundant rainfall, the central Pacific receives moderate rainfall, and the coast of Peru remains dr y. Other
years, when El Niño conditions set in, this rainfall pattern shifts eastward. Tall rain-producing clouds
form in the central rather than western Pacific, causing shor tages of rain and sometimes even drought
in par ts of the western Pacific. At the same time, rainfall increases dramatically in the central and
sometimes eastern Pacific. In French Polynesia, for example, hurricanes become more frequent. These
changes in the cloud and precipitation patterns are a result of changes in the winds and currents that
occur when El Niño conditions develop.
I
Sign In
after reading page 5 in your booklet.
Your Teammates:
Crew Name:
Your Name:
Your Role:
Climate Variable Under Investigation:
Observe the System
✔ Clouds/Precipitation
❏ Currents ❏ Pressure ❏ Wind ❏
after reading pages 6–8 in your booklet.
1. Identify three impacts of El Niño.
2. Identify the two dominant sea surface temperature (SST) features and explain how they evolve.
3. Describe the present sea surface temperature pattern.
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.
Clouds/Precipitation Worksheet
Establish a Hypothesis
page 2
after reading page 8 in your booklet.
What is your hypothesis?
Collect and Analyze Data
after reading pages 9–10 in your booklet.
1. Follow these basic steps to complete your investigation on Clouds/Precipitation. Then, answer the questions
below. Dr. Enso will give you all the detailed instructions you may need to complete your repor t.
• Use the Instructional Terminal to watch three movies about Clouds/Precipitation:
Introduction: Describes how cloud and rainfall patterns in the tropical Pacific var y between non El Niño
and El Niño conditions. Uses cloud type to describe climate changes.
Precipitation Index Maps: Describes how precipitation index maps are developed and how they are interpreted.
Patterns: Describes how precipitation patterns change between non El Niño and El Niño conditions. Uses
maps of the precipitation index to illustrate differences.
• Use the Data Center to build a map of the precipitation index for the Pacific Ocean. Sources for
precipitation index data include: satellite, ships of oppor tunity, the Glomar fleet, island stations,
and on board the ship.
• Use the Data Archive to analyze your precipitation index map and compare it to historical maps.
• Confirm or refute your hypothesis with your team.
• Complete your repor t to Dr. Enso at the Com Center.
2. Describe the overall precipitation patterns of the tropical Pacific.
3. How do the present patterns compare to El Niño and non El Niño conditions?
4. If another ship in the fleet is studying currents, see if your precipitation index data are consistent with the currents data.
Why or why not?
Submit Your Conclusions
after reading page 11 in your booklet.
1. What is the present state of the climate system?
2. What evidence do you have to support your claim?
3. Does this claim support or refute your hypothesis?
Permission granted to copy for classroom use only. © Planet Earth Science, Inc.