As the basis of the marine foodchain, phytoplankton are
important indicators of change in the oceans. These marine flora
also extract carbon dioxide from the atmosphere for use in
photosynthesis, and play an important role in global climate.
Phytoplankton blooms that occur near the surface are readily
visible from space, enabling a global estimation of the presence
of chlorophyll and other pigments. There are more than 5,000
different species of phytoplankton however, and it is not always
possible to identify the type of phytoplankton present using
space-based remote sensing.
Coccolithophores, however, are a group of phytoplankton that
are identifiable from space. These microscopic plants armor
themselves with external plates of calcium carbonate. The
plates, or coccoliths, give the ocean a milky white or turquoise
appearance during intense blooms. The long-term flux of coccoliths
to the ocean floor is the main process responsible for the formation
of chalk and limestone.
This image is a natural-color view of the Celtic Sea and English
Channel regions, and was acquired by the Multi-angle Imaging
SpectroRadiometer's nadir (vertical-viewing) camera on June 4, 2001
during Terra orbit 7778. It represents an area of 380 kilometers
x 445 kilometers, and includes portions of southwestern England and
northwestern France. The coccolithophore bloom in the lower left-hand
corner usually occurs in the Celtic Sea for several weeks in summer.
The coccoliths backscatter light from the water column to create a
bright optical effect. Other algal and/or phytoplankton blooms can
also be discerned along the coasts near Portsmouth, England and
Granville, France.
At full resolution, evidence of human activity is also apparent
in this image. White specks associated with ship wakes are
present in the open water, and aircraft contrails are visible
within the high cirrus clouds over the English Channel.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC.
The Terra satellite is managed by NASA's Goddard Space Flight Center,
Greenbelt, MD. JPL is a division of the California Institute of
Technology.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
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