Vertical Distribution of the Mirror Image Returns Observed by TRMM PR and Estimated for a 35-GHz Radar

Abstract

The vertical distribution of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR)-observed precipitation reflectivity and their mirror image (MI) reflectivity are outlined in this paper. The purpose of this study is to investigate the possibility and the limitation of the MI method, which can be used to estimate rain attenuation. Because the MI returns are attenuated much more greatly than the direct image returns, and also because the MI return is affected by the surface reflection and surface scattering, the MI returns are much smaller and more complex than the direct image (DI) returns. However, because the MI returns might be contaminated by the surface or contributed by bistatic scattering near the surface, there are many strong mirror returns between the surface and below surface at 1 km. The ratio of detectable MI return pixels to detected DI return pixels depends on rain rate, target height, and storm height. In addition, differences also exist between the convective and stratiform rain. The reason for this might be because the difference of the surface cross section and the difference of the storm height between the two types of rainfall. Furthermore, the direct and the mirror returns for a 35-GHz radar are also estimated. The virtue of the MI method of the Ka-band radar may reside in expanding the dynamic range of the MI method from 4?30 to 0.6?30 mm h?1.