Understanding passive microwave and radar signatures of rapidly intensifying tropical cyclones: observations and model simulations for process understanding

Due to its ability to infer precipitation structure, passive microwave satellite imagery has been put forth as a potential observational tool to predict episodes of tropical cyclone (TC) rapid intensification (RI). RI has been linked to the occurrence of a host of precursor structural features within the TC core that can be observed in passive microwave and radar imagery, such as features that are azimuthally asymmetric (vortical hot towers, convective bursts) and symmetric (ring features).

To better understand the linkages between observed spatial and temporal variability in passive microwave brightness temperatures, and storm dynamics during RI, 1-km Weather Research and Forecasting (WRF) model simulations have been performed of Hurricane Earl (2010) and Hurricane Ike (2008), which underwent RI under greater than and less than 10 kt of shear respectively. The WRF output is processed with the University of Nagoya Satellite Data Simulator Unit (SDSU) to simulate passive microwave brightness temperatures at typical satellite frequencies and radar reflectivities at multiple frequencies (S/Ku/Ka/W) during the RI phases of each storm. This framework will allow the degradation of the resolution of the data to satellite spatial and temporal resolution to examine detection issues at observable time and space scales, and as a function of future satellite observing networks. The azimuthal distribution and intensities of precipitation features in simulated remote sensing products of these RI events will be related to observed passive microwave structures and radar reflectivities observed during the NASA Genesis and Rapid Intensification Processes (GRIP) 2010 field campaign and the 22-year HURSAT-MW SSM/I and TMI passive microwave satellite overpass database to better understand the utility of passive microwave imagery to understand convective modes and organization during RI.