Download Oceanographic Applications

History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Trends
Earth Remote Sensing*
Definition: The use of electromagnetic radiation
(EMR) to acquire information about the ocean,
land and atmosphere without being in physical
contact with the object, surface, or phenomenon
under investigation (Martin, 2004).
Unlike in situ measurements, the
geophysical quantity of interest derived
from remote sensing is inferred from the
properties (intensity, polarization, spectral
signatures) of the reflected or emitted
radiation.
* The term ”Remote Sensing” was coined by Dr. Evelyn Pruitt, ONR, in the 1940s
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Trends
Satellite-borne sensors record emitted and/or reflected radiation, and
ocean features are inferred from the radiation measurements
Ocean color
Ice concentration
Ship wakes
Oil slicks
Coral reefs
Passive
Reflected
Emitted
Sea surface temperature
Surface wind speeds
Ice concentration
Night time lights
Transmitted
Reflected
Active
Active sensors are both
source and receiver of the radiation
Sea sfc height
Surface winds
Wave heights
Ice conc., age
Oil slicks
Ship wakes
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Trends
Ocean Remote Sensing
What are we sensing?
Electromagnetic Radiation (EMR)
What phenomena do we infer
from the radiation measurements?
visible
infrared
microwave
Chlorophyll, Sea Ice
Oil Slicks, Shoals
Surface Temperature
Ice Concentration
Surface Winds
Sea Level
Wave Heights
We use the visible, infrared, and microwave
portions of the electromagnetic spectrum
Microwaves are usually
denoted by frequency
(gigahertz)
Visible and IR are usually
denoted by wavelength
(microns or nanometers)
http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap03/FG03_09.jpg
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Trends
Satellite-borne sensors record emitted and/or reflected radiation, and
ocean features are inferred from the radiation measurements
Passive
Visible solar radiation
reflects from Earth’s surface
and from particles and
organisms in the ocean.
The Earth (land, ocean, and
atmosphere) emits infrared and
microwave radiation.
Active
Most active sensors transmit microwave
radiation and receive some of the energy
which reflects back from Earth’s surface.
There are two new satellites (ICESat and
CALIPSO) which use lidar (visible and
infrared lasers) for Earth remote sensing.
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Oceanographic Applications and
Primary Satellites / Sensors
Application
Sensor Type
Satellite / Sensor
Sea Surface
Temperature
Infrared Radiometer
(passive)
POES / AVHRR
Aqua / MODIS
Ocean Color
Multispectral Radiometer
(passive)
SeaWiFs
Aqua / MODIS
Sea Surface Height
Altimeter
(active)
JASON-1
ENVISAT / RA-2
GFO
Ocean Surface Winds
Scatterometer (active),
Polarimetric Radiometer
(passive)
QuikScat
Coriolis / Windsat
Sea Ice
Microwave Radiometer
DMSP / SSM/I
(passive)
POES / AMSU-B
Synthetic Aperture Radar Radarsat-1
Trends
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Ocean Color Observations
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/IMAGES.html
Trends
• Visible light emitted from the sun
reflects off suspended particles
Coastal Upwelling
Oregon & California
6 October 2002
NASA / Terra MODIS
• Based on the nature and quantity of
this reflected light, we can make
estimates of chlorophyll concentration
(primary productivity) and water clarity
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Trends
Diatoms
From www.dnr.state.md.us
•
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Most abundant plankton
Nutrient rich, high latitudes
2-1000 m
autotrophic
chlorophyll in chloroplasts –
absorb red and blue
Appear yellow-brown (“Golden
Algae”)
Diatom Bloom off mid-Atlantic coast
(from http://seawifs.gsfc.nasa.gov/)
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Dinoflagellates
Ceratium
50 m
Red Tide
• Unicellular
• Autotrophic,
heterotrophic or
mixotrophic
• Rapid reproduction can
lead to red tides
• Some produce
neurotoxins
Trends
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Coccolithophorids
http://oceancolor.gsfc.nasa.gov/cgi/image_archive.cgi
•
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Shells composed of calcium
coccoliths – milky white appearance
Able to thrive in nutrient-poor
conidtions
Photo by Kurt Buck, 1995
http://www.mbari.org/~reiko/work/phyto.htm
Trends
TERRA MODIS, 21 JUN 04:
Coccolithophore blooms off of Iceland
http://visibleearth.nasa.gov
50 km
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Ocean Color Applications
• Ocean Color features are caused by scattering and
absorption of visible wavelengths by:
– Plankton (also emit certain wavelengths)
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Represent 25% of global vegetation
Provide food for zooplankton and fish
Convert CO2 into carbon; important in global carbon cycle
Harmful Algal Blooms
– Colored Dissolved Organic Matter (CDOM) or “Gelbstoff” –
organic runoff, detritus, decaying matter
– Sediments, Pollutants
• Ocean optical properties (scattering and absorption)
affect swimmer visibility, submarine vulnerability, and
performance of electro-optical systems (underwater
video, laser)
• Features indicate positions of fronts, eddies, and
direction of currents
Trends
History / Impact
EM Radiation
Ocean Features
Orbits / Satellites / Sensors
Oceanographic Remote Sensing
• Satellite remote sensing has revolutionized
oceanography, opening our eyes to energetic
small scale (50-200 km) processes
• A wide variety of observations are available
• Some observations, such as sea ice
concentration, are now available for relatively
long periods of time (~30 years)
• Applications support scientific, commercial
and military interests
Walter Munk: “1 + 1 = 3” (When satellite data is combined with
in situ ocean observations, the resulting info is worth more than
the sum of two separate measurements).
Trends
Links
• Imagery from NASA
– Visible Earth: http://visibleearth.nasa.gov/
– Earth Observatory (including “Image of the Day”):
http://earthobservatory.nasa.gov/
• Imagery from NOAA
– Geostationary Satellite Server: http://www.goes.noaa.gov/
– CoastWatch: http://coastwatch.noaa.gov/cw_index.html
• NOAA NESDIS Education and Outreach
– http://www.nesdis.noaa.gov/outreach_edu.html
• NASA Remote Sensing Tutorial
– http://rst.gsfc.nasa.gov/
• Visualization of Satellites on Orbit
– http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html
Links
• Ocean Color
– Brief Overview: http://disc.gsfc.nasa.gov/oceancolor/index.shtml
– Data and Imagery Gallery: http://oceancolor.gsfc.nasa.gov/
–
http://nasascience.nasa.gov/earth-science/oceanography/living-ocean/remote-sensing
• Sea Surface Temperature, Topography, Winds
– NASA JPL: http://podaac-www.jpl.nasa.gov/
• Overview of POES and GOES (NOAA)
– http://www.nesdis.noaa.gov/satellites.html
• DMSP Program
– Historical Overview:
http://www.aero.org/publications/crosslink/winter2005/02.html
– Data Archive, Research, Products:
http://www.ngdc.noaa.gov/dmsp/index.html
• NPOESS Program
– http://www.npoess.noaa.gov/
• CORONA Program
– http://www.nro.gov/corona/facts.html