Simulation-Based Analysis of the Error Caused by Non-Uniform Beam Filling and Signal Fluctuation in Rainfall Rate Measurement with a Spaceborne Radar

[摘要] We focus on two rainfall measurement algorithms which will be used with a spaceborne radar for the Tropical Rainfall Measuring Mission. One is the conventional rainfall measurement algorithm (Z method), which uses the radar reflectivity factor, and the other is the surface reference technique (SRT method), which uses rain attenuation. Non-uniform beam filling (NUBF) is one source of error in the above methods. This paper investigates the error caused by NUBF using a computer simulation that employs rain data measured by a ground-based radar. The simulation shows that the Z method always overestimates the rainfall rate, and the SRT method almost always underestimates the rainfalll rate. The simulation takes into consideration the effect of the signal fluctuation. The results show that the effect of the signal fluctuation is larger than that of the NUBF, in both the Z method and the SRT method. In particular, the signal fluctuation causes serious errors in rainfall rate estimation by the SRT method in light rain.

[学科分类] 大气科学