Rainfall and Convection Asymmetries of Tropical Cyclones from TRMM Precipitation Radar Observations

Rainfall and convection asymmetries of tropical cyclones (TCs) are examined using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) observations. Due to its narrow swath width (around 250 km), not all TC overpasses by the PR can directly sample the storm center and inner core region. In this study, a subset of about 1000 manually re-centered TC overpasses with the inner core region well-observed by the PR will be used. The dataset is divided by future 24-hour intensity change including rapid intensifying (RI), slowly intensifying, neutral, and weakening, and exclusively includes storms with at least moderately favorable environmental conditions. A wavenumber analysis is applied to the dataset to calculate the Fourier coefficients of the PR near surface rain rate, and near surface, 4-km, 8-km, 12-km, and 16-km reflectivities within 100 km radius from the storm center. The composite radial distributions of wavenumber 0 (azimuthal mean) near surface rainfall and reflectivities in different levels will be compared for different storm intensity and future intensity change stages. Similarly, the composite 2-D distributions of wavenumber 1, and 2 amplitudes of these parameters will also be compared. Special attention will be given to the rapid intensifying category to see if the degree of symmetry of rainfall and convection in the inner core is higher for RI storms than storms in other future intensity change stages.