Examination of surface cross section statistics over ocean and land

Weather radars that operate at frequencies higher than about 3 GHz can he affected adversely by rain attenuation. However, for spaceborne applications, where the size and mass of the antenna are limited, adequate spatial resolution can be obtained only by increasing the frequency. For the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR), the use of 13.8-GHz frequency with a 2-m antenna size represents a compromise between the desire to minimize the antenna size and rain attenuation and maximize the spatial resolution. As demonstrated by Hitschfeld and Bordan (1954) in their classic study, estimates of rain rate from a single-attenuating wavelength radar are unstable when the path attenuation is large, unless the radar constant and the drop size distribution are known to a high degree of accuracy. Because these conditions are seldom met, an alternative strategy is needed to complement the Hitschfeld-Bordan method for moderate and high rain rates. One of the proposed ways of estimating attenuation is the surface reference technique (SRT). In this work, the data from TRMM PR is used to study the statistical characteristics of the surface return (s0) as a function of the surface type (ocean/land) and incident angles during rain and rain-free times, this analysis is further used to study the effectiveness of using surface return as the reference.