Classification and quantification of TRMM radar observations

Abstract

A better knowledge of precipitation types and their radar reflectivity structures is important for interpretation of space-borne radar observations as well as microphysical processes for improving satellite precipitation algorithms. The differences in microphysics, or drop size distributions lead to different reflectivity rain rate relationships for convective and stratiform clouds. While this approach is simple for convective/stratiform classification to rain profiles and suitable for estimating profiles of latent heating, it does not address a variety of problems. Raindrop size distributions can vary widely within the convective and stratiform categories themselves. Research that goes further into classifying precipitation profiles can bridge this gap. The fundamental observation of space-borne radar is the vertical profile. All inferences and classifications must start there. Classifying rainfall by the three-dimensional structure of its reflectivity field offers the potential to reduce both random and systematic errors in raindrop size distributions assumed in rainfall retrievals. This research attempts to address the specific and unique problems that exist in the field of space-borne radar observation of precipitation profiles on a global scale. The difficulty in modeling the precipitation profile can be attributed to the lack of validated data on a global scale to guide this work. It is likely that long-term research will be required to fully develop the concepts introduced in this work. This effort only takes the first step in defining such an outline. Extensive experimental verification in a wide range of regions is required to validate the usability of new derived techniques. The main goal of this research is to use the vertical structure of the observed radar reflectivity field, in an information theoretic framework, to extend rain-type classification beyond convective/stratiform separation and to define a natural classification for radar reflectivity profiles that can eventually be related to microphysical variability of precipitation profiles. The classification of precipitation type to convective/stratiform rain type from space-borne precipitation radar observation and 2-dimensional wavelet analysis is first introduced in this research. Subsequently this dissertation includes the study of the classification of the self-organizing map of TRMM-PR rain profiles on a global scale, the global study of bright band structure as well as the study of the variability of raindrop size distribution.