The structure of tightly packed "closed cells" in a layer of marine stratocumulus
over the southeastern Pacific Ocean are highlighted in these views from the
Multi-angle Imaging SpectroRadiometer. Closed cell clouds are formed under
conditions of widespread sinking of the air above. As heat is radiated to the
atmosphere, the top of the cloud cools. The cool air sinks along the cell boundaries
and this sinking motion perturbs the shallow cloud layer into interesting structures
such as those shown here. These cells are notably small, with diameters ranging from
10-15 kilometers, instead of the 15-45 kilometers typically noted in satellite
observations. The dark areas along the cell boundaries are also cloudy and do not
indicate clear sky. Closed cell clouds are found in high pressure systems characterized
by weak winds, and are thought to occur preferentially over cold ocean waters. The
image covers an area of about 280 kilometers x 227 kilometers.
An overview image showing some of the meteorological context, and a natural-color and
inverted image pair are also provided. The cell structure and the distinctive radial
patterns indicative of the sinking air motions are easier to see clearly in the inverted
view. The area covered by the overview on the left is 274 kilometers x 463 kilometers,
while the right-hand images each cover 278 kilometers x 62 kilometers. All of the images
were created with data from MISR's vertical-viewing (nadir) camera, and were acquired
on November 19, 2001 (during Terra orbit 10228). The scenes are centered roughly at
38 degrees south latitude and 118 degrees west longitude.
Low-lying marine stratocumulus clouds are important components in the Earth's energy
budget because they are bright and abundant, and reflect a large amount of solar energy
toward space. They are difficult to represent in climate models however, due to their
variable structure and rapid changes in reflectivity over short distances.
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.
|
