Structural Morphology of Tropical Cyclones as Witnessed by Passive Microwave Sensors

With the advent of NASA's Global Precipitation Measurement (GPM) mission and its host of associated passive microwave sensors being put into orbit during the early part of this decade, these platforms have become a focal point for their potential in improved understanding of meteorological processes as well as enhanced forecast products. One such potential phenomena of study of note is tropical cyclones, which are especially challenging for the meteorology community due to their typical occurrence over open oceans with a lack of observational platforms in the vicinity, as well as the systems potential for major damage and loss of human life. Recent works have suggested utility in passive microwave platforms improved estimates of storm centers as well as the presence of convective features detectable by passive microwave platforms related to intensity change (e.g. convective burst presence and convective symmetry).

Here we evaluate past passive microwave data spanning 1987-2008 from the Special Sensor Microwave/Imager (SSMI) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) at both lower-frequencies (i.e. 37 GHz) and higher-frequencies (i.e. 85 GHz) to evaluate the role of emission from liquid and scattering from frozen hydrometeors. This is accomplished through the use of a computationally efficient, automated algorithm that can detect contiguous precipitation features and relate morphological metrics about these features. These estimates can then be applied to a host of different uses examined here for tropical cyclone study including: improved center-fixes, rapid intensification prediction algorithms, and new perspectives on precipitation organization in tropical cyclones.