Download Ocean Currents PowerPoint

Ocean Currents
Surface Currents
&
Deep Currents
THE RUBBER DUCK JOURNEY:
JANUARY 10, 1992: Somewhere in the middle of the Pacific Ocean nearly 29,000 First
Years bath toys, including bright yellow rubber ducks, are spilled from a cargo ship in the
Pacific Ocean.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
NOVEMBER 16, 1992: Caught in the Subpolar Gyre (counter-clockwise ocean current in the
Bering Sea, between Alaska and Siberia), the ducks take 10 months to begin landing on the
shores of Alaska.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
June 16, 1995: The ducks take three years to circle around. East from the drop site to
Alaska, then west and south to Japan before turning back north and east passing the original
drop site and again landing along the coast of Washington state.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
July 30, 1996: A duck washes up in the Kure Islands, in the middle of the Pacific.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
April 9, 1997: A duck makes its way to the small Hawaiian Island of Lanai.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
1995 to 2003: Some ducks head North, through the Bering Straight and into the frozen
waters of the Arctic. Frozen into the ice the ducks travel slowly across the pole, eastward.
Ducks begin reaching the North Atlantic where they begin to thaw and move Southward.
July 3, 2003: A duck finally washes up on the east coast of the U.S. on the coast of Maine.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
THE RUBBER DUCK JOURNEY:
July 15, 2007: The first rubber duck finally reaches England.
75N
90N
60N
45N
30N
15N
0
0
30E
60E
90E
120E
150E
180
150W
120W
90W
60W
30W
0
YouTube Duck Song
• https://www.youtube.com/watch?v=RPUmRmdcjw
Surface Currents
Surface Currents
What about debris from the
Japan tsunami?
• Video clip of tsunami debris hitting the U.S.
Surface Currents
• Horizontal, stream like movements of
water that occur at the surface of the
ocean.
• Ex: Gulf Stream is 100 miles wide; 2,000
feet deep with a max speed of 5mph
3 Factors that Influence
Surface Currents:
• Global Winds
• Coriolis Effect
• Continental Deflection
Deep Ocean Currents
• Caused by differences in density
(temperature & salinity)
• Move along ocean bottom from poles to
equator. (avg speed = 8 miles a day)
• Ex: Polar Creep
Deep Ocean Current
Mixing of Surface & Deep Currents
• Very little mixing occurs between surface
and deep currents. (thermocline
temperature zone)
• Upwelling: Winds move warm surface
water away allowing cold deep water to
move up and replace it. Brings nutrients
and minerals to the surface which feed
plankton.
Ocean Temperature Layers
Upwelling
El Nino Activity
El Niño of the late 1990s
It rose out of the tropical Pacific in late 1990s. By the time it had run its course the giant El Niño of the
late 1990s had changed weather patterns around the world, killed an estimated 2,100 people, and
caused at least 33 billion [U.S.] dollars in property damage.
Along the coast of Peru (west coast of South America) weeks of heavy rain caused coastal rivers to
flood their banks, five or six inches of rain a day in some places. Peru was where it all began, but El
Niño’s abnormal effects on climate (including: sunshine, temperature, atmospheric pressure, wind,
humidity, precipitation, cloud formation, and ocean currents) changed weather patterns across the
equatorial Pacific and in turn around the globe. Indonesia and surrounding regions suffered months of
drought. Temperatures reached 108°F in Mongolia; Kenya’s rainfall was 40 inches above normal;
central Europe suffered record flooding; and Madagascar was battered with monsoons and cyclones. In
the U.S. mudslides and flash floods flattened communities from California to Mississippi, storms
pounded the Gulf Coast, and tornadoes ripped Florida.
Aside from the climate related disasters the El Niño of the late 1990s caused it also marked the first
time that climate scientists were able to predict abnormal flooding and droughts months in advance,
allowing time for threatened populations to prepare. Perhaps the most important effort was the
development of the TAO (tropical atmosphere/ocean) array of 70 moored buoys to span the equatorial
Pacific. They monitor water temperature from the surface down to 1,600 feet [500 meters]. Thanks to
the TAO buoys, and a variety of other tools, climate scientists now have information of unprecedented
range and accuracy, which has enabled them to confirm and expand their theories about what occurs
both during normal weather patterns and the arrivals of El Niño.
Buoy Location Across the Pacific Ocean
Normal Conditions (Equatorial Pacific)
The climate in the equatorial Pacific is usually determined by sunlight heating the surface zone of the
western Pacific around Australia and Indonesia, causing huge volumes of hot, moist air to rise
thousands of feet creating a low-pressure system at the ocean’s surface. As the air mass rises and
cools, it sheds its water content as rain, contributing to monsoons in the area.
Now much drier and higher in the troposphere, the air heads east, guided by winds in the upper
atmosphere, cooling even more and increasing in density as it travels. By the time it reaches the west
coast of the Americas, it is cold and heavy enough that it starts to sink, creating a high-pressure
system near the water’s surface. The air currents then flow as trade winds back toward Australia and
Indonesia. As the trade winds blow westward over the Pacific, they push the warm top layer of the
ocean with them, causing the hottest water to pile up around Indonesia. All along the coast of the
Americas, and especially off Ecuador and Peru, colder deep ocean currents upwells to replace the
warm water that was carried away by the global winds, bringing to the surface nutrient rich water
from the deep ocean. That wealth of nutrients from the deep ocean sustains an enormous food web
and makes the coastal waters off Peru one of the world’s best for fishing.
El Nino Conditions (Equatorial Pacific)
El Niño changes all that. For reasons that scientists still do not understand, every few years the trade
winds weaken or even disappear. Without the trade winds the warm top layer of the eastern Pacific
does not move west. It stays in place, getting hotter and hotter. This causes the humid air above the
extremely warm ocean to rise and condense as torrential rain on the west coast of the Americas.
This, in turn, reduces the salinity of the coastal seas, where deep ocean upwellings have already
stopped. Marine life that customarily thrives on upwellings off Ecuador and Peru now search for
cooler, richer waters.
Because El Niño moves the rains that would normally soak the western Pacific toward the Americas,
such places as Australia, Indonesia, and India may experience severe drought. Meanwhile, back in
North America, the jet streams that travel 5 to 8 miles above Earth’s surface shift dramatically. The
polar jet stream tends to stay farther north over Canada than usual; as a result, less cold air moves
into the upper United States.
El Nino Summary
• Predictable, occurring every 2-12 years
• The South Pacific Trade Winds slow down or stop, moving
less warm tropical water to Australia & Indonesia.
• Temps rise along the west coast of South America
• Stops upwellings along South America, which means no
nutrients, disrupting the food chain.
• Affects ALL life in ocean & on land
• Change between ocean & atmosphere cause global
climate change.
El Nino’s Affect on Global Climate
• Dry conditions in the western Pacific
(Australia & Indonesia)
• Heavy rainfall in South America (Peru) &
Southern U.S.
• Mild winter temperatures in Northern U.S.
El Nino