Performance characteristics of a spaceborne precipitation radar over an ocean validation site

This dissertation attempts to evaluate the TRMM satellite observations over an open ocean site. Guam was chosen as one of the ground validation sites and my dissertation focuses on precipitation measurements observed around Guam. There is a dearth of literature and documentation describing the procedures and methodology for comparison of ground and spaceborne precipitation measurements. I provide a detailed description of the ground validation data and algorithms used to developed a satellite ground validation site.; The viewing geometry of the TRMM measurements is very complicated. This is amplified by the fact that the ground radar data also have a complicated sampling geometry and point measurements from rain gauges are generally not representative of areal sampling of the TRMM and ground radar observations. Careful consideration must be given to the method used for comparison. I develop a methodology to compare spaceborne and ground based observations in a common reference frame.; The results show that Guam radar rainfall estimates provide reasonable results when compared to rain gauge data. Long-term rainfall accumulations indicate small range dependence in the Guam radar rainfall at far ranges because of the interaction with the melting level. Average rainfall rates for near surface and 2 km level products increase with increasing scan angle from nadir. Storm height and frequency of precipitation analyses also indicate and increase in value with increasing scan angle.; Vertical profile of reflectivity analysis shows that Guam radar and PR agree within +/− 1 dB except at the very lowest altitudes where PR is about 2 dB too low because of attenuation. Rainfall comparisons show that PR rainfall rates are over a factor of two lower than ground based measurements. Because of the lack of sensitivity, the TRMM PR is unable to detect about 26% and 73% of the echo at low and high altitudes, respectively. Results show that TRMM PR is able to capture the seasonal rainfall cycle but not the diurnal cycle on Guam.