Footprints of Storms on the Sea in the JERS-1 SAR Image

概要

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SEASAT synthetic aperture radar (SAR) echoes from the sea show beautiful images of storms over the ocean. However, the mechanisms by which such storm images are created have not yet been revealed very well. The core of these images is usually an echo-free hole which is attributed to the damping of the radar-detectable short gravity waves by the intense rain in the storm core. The bright area surrounding the core is believed to be caused by strong winds diverging from the downdraft which is collocated with the intense rain. The outer boundary of the bright area has been found to be associated with the classical gust front. During the Tropical Ocean Global Atmosphere/Coupled Ocean-Atmosphere Response Experiment (TOGA/COARE), continuous observations of rain by shipborne radars were carried out. One image of JERS-1 SAR taken in this period contains storms that were within the observation area of a shipborne radar. The SAR image and the rain-radar image are compared. Even though the signal-to-noise ratio of the SAR image is very low, there is good correspondence between heavy rain areas and some of the dark areas in the SAR image. The boundary of a rain-induced dark area is found to correspond approximately to the radar reflectivity factor (Z-factor) of 35 dBZ or 5.5 mm/h of rain.
社団法人電子情報通信学会の論文
1995-12-25