A data processing to reduce the errors of rainfall rate measured with spaceborne radar

Spaceborne rain radars may be operated with a fairly low S/N (signal to noise ratio) condition, because of several hardware limitations and the large distance between radar and target. The rain radar does not directly measure the rain echo power, instead, it measures the total received power which is the sum of the rain echo power and the receiver noise power. The rain echo power is obtained by taking the difference between the total received power and the receiver noise power. The experimentally obtained rain echo power is sometimes estimated to be the negative value on the low S/N condition. The rainfall rate can not be directly estimated from this negative data. Three data processings, which are the truncation, the zero rain and the negative rain method, are applied to the rainfall rate estimation from the negative data. The zero rain method is effective for reducing the errors of the rainfall rate and its statistic