Three-dimensional validation at TRMM ground truth sites: Some early results from Darwin, Australia

The Tropical Rainfall Measuring Mission (TRMM) has been designed to obtain quantitative precipitation measurements from space within the tropics on a global scale. We have undertaken a pilot study to derive a three-dimensional surface verification data set from a typical month of data, integrating all the available data products collected at a particular station. The goal is to determine, with the minimum amount of data processing, not only the amount of precipitation, but also its subdivision into convective and nonconvective (i.e., stratiform) components and its vertical structure. For this pilot study we use the data obtained at Darwin, Australia during February 1988. We present methods for distinguishing convective and nonconvective regions, establishing the Z-R relations that apply to each region, and determining the fractions of convective and nonconvective rain that contribute to the total precipitation. We will further investigate the sensitivity of the results to the spatial resolution of the radar data.