Simultaneous observations of rain cells over the ocean by the synthetic aperture radar aboard the ERS- 1/2 satellites and by weather radars

Abstract

We present three pairs of concurrent images of rain cells over the sea which have been acquired by the C-band synthetic aperture radar (SAR) aboard the European Remote Sensing Satellites ERS-1 and ERS-2 and by local weather radars. By comparing these data sets we find that the part of the radar signature caused by the wind gusts associated with the rain cell usually covers a much larger area than the part of the radar signature caused by the impinging raindrops. Furthermore, in the center of the quasi-circular patterns visible on SAR images of the sea surface, often areas are encountered that have an enhanced or a reduced roughness relative to its surroundings. We conjecture that this is caused by the spatial and temporal variability of the rainfall within the rain cell.