Cloud-top radiance and height characteristics of Hurricane Isabel are
depicted in these data products and animations from the Multi-angle
Imaging SpectroRadiometer (MISR). Isabel was upgraded to hurricane status a few
hours after the top image panels in this set were acquired on September
7, 2003. By the time the bottom panels were acquired on September 11,
Isabel was a strengthening category 4 hurricane, centered about 900 kilometers
east-northeast of the Leeward Islands.
Along the left are radiance images from MISR's vertical-viewing (nadir)
camera, at center are cloud-top height fields, and the right-hand panels
provide retrieved local albedo values. The cloud-top heights are
retrieved using automated stereoscopic processing of data from multiple MISR
cameras, and are uncorrected at this stage for the effects of the
exceptionially high winds associated with the hurricane's rotation.
Albedo values are dependent upon the observed cloud radiances as a
function of view angle and upon the cloud height field, and are
well-represented here. Albedo is a function of the amount of sunlight
reflected back to space divided by the amount of incident sunlight. Cloud
height and albedo are among the principle variables governing the
influences of clouds on climate. Areas where height and albedo could not
be retrieved are shown in dark grey.
The animations are created with radiance imagery from all nine MISR
cameras, from the most steeply forward-viewing to the most steeply
backward-viewing. Hurricane Isabel's counter-clockwise rotation over
the course of the seven minutes required for all nine cameras to view the
scene can be observed, and the multiple perspectives provide a unique look
at cloud structure. For example, at the steeper look angles of the
7 September fly-over, thin clouds can be discerned above
the storm's eye. The loose structure and large, ragged eye of Tropical
Storm Isabel on the 7th contrasts with the well-developed eyewall, deep
convective clouds and strong rotation of Hurricane Isabel on the 11th.
Click here to download an MPEG version of the Hurricane animation.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously from pole to pole, and every 9 days views the entire globe
between 82 degrees north and 82 degrees south latitude. These data
products were generated from a portion of the imagery acquired during Terra
orbits 19793 and 19852. The panels cover an area of about 360 kilometers x 560
kilometers, and utilize data from blocks 77 to 80 and 72 to 75 within
World Reference System-2 paths 218 and 230, respectively.
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.
Text acknowledgment: Clare Averill (Raytheon/Jet Propulsion Laboratory).
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