As summer rapidly approaches in the Southern Hemisphere,
tiny marine plants are taking advantage of the long days
by growing vigorously. These images were acquired by the Sea-viewing
Wide Field-of-view Sensor (SeaWiFS) on December 8, 2002. The top true-color
image shows how the masses of phytoplankton
color the water between the east coast of South America and the Falkland Islands.
Green and black water indicates the presence of the highest concentrations of
phytoplantkon. Chlorophyll causes the green color. In black water, the
phytoplankton are absorbing so much sunlight for food that only a little bit of light
is reflected back to space. Water tinted brown is filled with sediment flowing from river mouths
into the sea. The brightest areas are probably coccolithophores—plants with calcium
carbonate shells that reflect light strongly.
The bottom image shows chlorophyll concentration, a measurement of
the amount of phytoplankton. This area is particularly rich in phytoplankton
in part because of the convergence of the Malvinas and Brazil ocean currents.
The turbulent interactions of these currents bring nutrient-rich water to the
ocean surface, allowing the phytoplankton to take full advantage of the long days
and strong sunlight. For more information, read Convergence
Zones: Where the Action Is.
Image courtesy the SeaWiFS Project,
NASA/Goddard Space Flight Center, and ORBIMAGE
Ocean plants color the water of the Great Australian Bight off the shore of Victoria, Australia, in this photo-like Moderate Resolution Imaging Spectroradiometer (MODIS) image, taken by NASA’s Terra satellite on January 11, 2007.