An Analysis of Rapidly Intensifying Tropical Cyclones Derived from 13 Years of TRMM Data

In order to acquire a better understanding of the relationship between tropical cyclone (TC) core structure and future intensity change, 13 years of Tropical Rainfall Measuring Mission (TRMM) data were compiled for TCs in the North Atlantic and Eastern Pacific basins. TCs in each basin were separated and then divided into four categories dependent upon future 24-hour intensity change. Composites were made for each of the categories of weakening (W), neutral (N), slowly intensifying (SI), and rapidly intensifying (RI) TCs in order to assess structural differences in precipitation distribution, rainfall rates, microwave brightness temperatures, and infrared brightness temperatures.

TCs in each composite were normalized by shear direction assessed via the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis. The composites reveal areal coverage of precipitation is greatest (least) in the downshear left (upshear right) quadrant for each intensity change category in both basins. RI TCs feature greater areal coverage of precipitation in all quadrants than SI storms. Microwave brightness temperatures depict a similar trend. Results suggest although environmental conditions are very similar between SI storms and RI storms, increased frequency and symmetry of precipitation features favors greater rates of intensification.