NASA and the Japanese Space Agency's Tropical Rainfall Measuring Mission (TRMM) satellite flew over the center of Super Typhoon Choi-Wan at 2:34 EDT on September 17, 2009 and captured heavy rainfall around the storm's center.
TRMM rainfall images are false-colored with yellow, green and red areas, which indicate rainfall between 20 and 40 millimeters (.78 to 1.57 inches) per hour. Dark red areas are considered heavy rainfall, as much as 2 inches of rain per hour.
Rain rates in the center of the swath are from the TRMM Precipitation Radar (PR), the only spaceborne radar of its kind, while those in the outer portion are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS).
Source: NASA/Goddard Space Flight Center
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