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UPWELLING BRINGS COLORFUL LIFE TO CALIFORNIA
COAST
A
NASA satellite penetrates the blue waters off the west coast
to reveal a spectacular image of a 700-mile long phytoplankton
bloom stretching from southern California to the middle of
Oregon. Phytoplankton represents the bottom rung of the ocean
food chain and consists of many diverse species of microscopic
free-floating ocean plants. The bloom was fed by an upwelling
that brought cold nutrient rich water to the ocean surface.
Upwellings occur regularly and often spawn large phytoplankton
blooms that nourish an incredible diversity of creatures.
DEEP
WATER FEAST: UPWELLINGS BRING NUTRIENTS TO THE SURFACE
The
upwelling around the California coast was brought on by winds
blowing southward along the west coast of the United States.
Friction and the effects of the Earth's rotation cause the
surface layer of the ocean to move away from the coast. As
the surface water moves offshore, cold, nutrient-rich water
upwells from below, replacing it. This upwelling fuel the
growth of marine phytoplankton which, along with larger seaweeds,
nourishes the incredible diversity of creatures found along
the northern and central California coast.
Sea-viewing
Wide Field-of-view Sensor (SeaWiFS) on board the Orbview 2
satellite captured the phytoplankton bloom October 6, 2002
(Images 1 and 2 above). Red represents high concentration
of chlorophyll, follow by orange, yellow and green. Land and
cloud portions of the image are presented in natural color.
SeaWiFS monitors ocean plant life by measuring the amount
of chlorophyll in the ocean.
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Image
3
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Caption
for Image/animation 3: Large phytoplankton blooms tend
to coincide with natural phenomena that drive that nutrient
rich water to the surface. The process is called upwelling.
Here's what's happening: winds coming off principal land masses
push surface layers of water away from the shore. Into the
resulting wind-driven void deeper water underneath the surface
layers rushes in toward the coast, bringing with it nutrients
for life to bloom.
It's different on the equator. There, water currents on either
side of the hemispheric dividing line are generally moving
in opposite directionsÜagain due to planetary rotation
and the Coriolis effect. As those currents rush past each
other they ostensibly "peel back" the surface of
the ocean, creating a void for deeper water to rush in and
take its place.
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