Extraction of rain parameters from ground-clutter echoes

The subject of this study to determine the extent to which the rainfall rate u/sub r/ (in mm/hr) can be determined by a polarimetry-sensitive radar from pre-determined ground-clutter echoes. Such echoes are modified by intervening rain as follows: they are decreased by cumulative attenuation during passage of the radar pulses to and from the target range cell, and they are modified by inextricable volume backscatter from raindrops in the range cell. The results of the study show that neglect of incoherent volume backscatter from the raindrops in a radar range cell located at the clutter target causes an error of 30 to 20% in estimating rainfall rates 21, between 5 and 120 mm/hr from a 5 km attenuation and phase change. In general, we need to extract both attenuation and phase change from the total received signal to draw conclusions about the rainfall rate. Additional use of Doppler capabilities may be necessary to suppress rain backscatter and thus to ensure the desired accuracy.