Using geographical information systems for the spatial analysis of base reflectivity radar data and applications to the study of tropical cyclone precipitation patterns

It is difficult to predict the rainfall patterns that a landfalling tropical cyclone (TC) will produce due to the many forcing mechanisms that can affect the distribution of moisture about the storm's center. Base reflectivity radar returns for these storms were examined to identify the spatial and temporal scales upon which these mechanisms affect precipitation distribution. Because of its ability to incorporate many layers of data, GIS is becoming a popular tool for climate research. As a pilot study towards the development of a radar-based climatology of landfalling TC precipitation patterns, I analyzed radar data within a GIS to investigate the rainfall patterns of 13 TCs in hourly intervals. I determined where precipitation was located about the center of each storm by overlaying a set of annular rings and quadrants over each radar composite and measuring such characteristics as storm orientation and elongation. This presentation discusses the spatial and temporal range over which the data could undergo analysis, appropriate time-interval for analysis, and the selection of a reflectivity level to serve as the perimeter for each polygon shape that was analyzed.