In the Arabian Sea, sunlight and nutrients has fueled a startling
occurrence of colorful phytoplankton and bacterial assemblages, which is
captured in these natural color images from NASA's Multi-angle Imaging
SpectroRadiometer (MISR). Several areas exhibit an unmistakably reddish
hue, particularly in the upper portion of the images. The image set is
centered along the Tropic of Cancer, about 400 kilometers east of Muscat,
Oman, and was acquired on October 2, 2004. A view from MISR's nadir
(directly downward viewing) camera is provided on the left, while the two
smaller images at the upper and lower right are from MISR's 60-degree
forward and backward pointing cameras, respectively.
The Arabian Sea is an unusual part of the world's oceans because it is
surrounded by land masses from three sides, and light levels in the region
are strongly influenced by cloud cover generated by the Indian monsoons.
Phytoplankton concentrations in the Arabian Sea tend to be highest during
September and October, towards the end of the summer monsoon. The offshore
drift of surface waters and their replacement by deeper, nutrient-rich
waters means that the Arabian Sea is very productive, but such
fertilization also sometimes results in copious phytoplankton production
and oxygen depletion of the subsurface waters. Although red phytoplankton
fluorescences have been associated with the low oxygen concentrations in
the intermediate and deep waters of the Arabian Sea, the red pigment in
this scene may instead be related to the dynamic processes of plankton
grazing and decomposition.
Multiple observation angles allow the color of surface ocean waters to be
studied in greater detail, and provides a method to observe regions that
can not be examined by satellite instruments that view nadir only, in cases
where the nadir view is affected by sun glint. In this case, the ocean
color in the lower right-hand corner is discernible at 60-degrees backward
but not at nadir. Multiple angles also enable the observation of ship and
cloud motion. The movement of several ships across the scene is illustrated
in an animation. The oblique imagery used in this image set is part of the
Local Mode data acquired during the Unified Aerosol Experiment United Arab
Emirates (UAE2) field campaign.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously and every 9 days views the entire globe between 82° north and
82° south latitude. These data products were generated from a portion of the
imagery acquired during Terra orbit 25483. The still image panels cover an
area of about 240 kilometers x 290 kilometers, and utilize Local Mode data
from within blocks 71 to 73 and within World Reference System-2 path
155.
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.