Analysis of Rainwater Flux in the Ifa during Toga Coare Using Shipboard Radar Rainfall Estimates

Fluxes in the warm pool region of the West Pacific Ocean play an important role in the determination of global climate. To better understand the relationships between the atmosphere and ocean in this region of the world, the Tropical Ocean Global Atmosphere (TOGA) program conducted the Coupled Ocean Atmosphere Response Experiment (COARE). During the Intensive Observing Period (IOP) of TOGA COARE, island - and ship-based observations were collected for a four month period. As part of this experiment, shipboard Doppler radar data were collected. These data were primarily collected to produce rainfall estimates for the TOGA COARE domain during the IOP. This dissertation explains the development of a high spatial and temporal resolution data set that was produced from the data collected by the MIT radar on the University of Southern California's R/V John V. Vickers. These data were quality controlled, and correction schemes were developed for both the reflectivity and radial velocity data. The corrected radar data were put into a fixed -space grid to remove the effects of ship motion. The data were gridded both in terms of reflectivity and rainfall rate. Careful processing of the data allowed for a high spatial grid resolution of 0.25 km by 0.25 km grid spacing. A temporal resolution of approximately 10 minutes was used, which matches the rate of data collection by the radar. The gridded rainfall rate data were integrated with respect to time to develop spatial distributions of accumulated rainfall over the grid domain. In addition, grid average rainfall were used to produce a time series distribution of rainfall. These distributions allowed for statistical analyses of rainfall to be performed. In particular, cruise average rainfall and diurnal variations in rainfall are examined. The gridded data were used to do case study analyses comparing rainfall during disturbed and undisturbed atmospheric conditions. In addition, disturbed cases were subdivided into stratiform and convective rainfall. The high resolution of the data allows for comparisons to be made with rainfall measurements collected by raingauges on buoys. A space -to-time conversion technique applied to moving echoes allows for a time series with increased temporal resolution.