Aspects of Hurricane Isabel
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.
An MPEG version of the Hurricane animation is available at the JPL Photojournal site.
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 use 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 Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
Text acknowledgment: Clare Averill (Raytheon/Jet Propulsion Laboratory).