Evaluation of 37 GHz Microwave Ring Pattern for Forecasting Rapid Intensification of Tropical Cyclones using SSM/I, SSMI/S and AMSR-E data

Over the past decades, tropical cyclones (TCs) track forecasts have been improved significantly. However, TCs intensity forecast, especially rapid intensification (RI) forecast, remains a challenging problem. One of the reasons is due to our limited understanding of the physical processes associated with RI process. Recently, a distinctive ring pattern in the inner core area of TCs has been found by Margie Kieper in the 37 GHz microwave images. She developed a subjective forecast method using the 37 GHz color product of the Naval Research Laboratory to predict the onset of RI. Following Margie Kieper's subjective forecast method, we have developed an automated detection method, 37 GHz ring pattern RI index, to identify the cyan-color ring pattern around the TCs center from the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) 37 GHz observations. The result shows that this ring pattern RI index is skillful for RI forecast in the Atlantic (ATL), East Pacific (EPA) and Western North Pacific (WNP) basins. In this study, this ring pattern RI index will continue to be applied to the past Special Sensor Microwave/Imager (SSM/I), the Special Sensor Microwave Imager / Sounder (SSMI/S) and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 37 GHz data to evaluate its role in RI forecast. We plan to use the SHIPS RI index (in ATL and EPA basins) and the environmental RI index (in other basins), such as SST and wind shear from the ECMWF INTERIM reanalysis data to screen out those ring cases with unfavorable environmental conditions. Finally, the SHIPS RI index and the environmental RI index will be incorporated into the 37 GHz ring pattern RI index to further advance the RI forecast skill of TCs.