| Description |
Despite improvements in recent years, tropical cyclone intensity change, and in particular differentiating intensification rates (especially rapid intensification, RI), remains an unresolved issue. Studies have quantified the importance of both environmental and convective properties with respect to intensity change; however, conjoined analyses have been rare. Using 15 years (1998-2012) of analysis information for Atlantic and East Pacific storms, we analyze environmental conditions to determine a threshold in which intensification is plausible. In conjunction with the environmental dataset, an expansive collection of passive microwave satellite data is used to investigate the relative importance of various convective properties (specifically those proxies for convective intensity, symmetry, and area). The Tropical Cyclone - Passive Microwave dataset (TC-PMW) statistics, and in particular, the spatial distributions of precipitation and intense convection (proxied using 85-91 GHz polarization corrected temperatures), are related to environmental conditions in an analysis of storms that meet the ""plausible"" threshold. Storms with higher intensification rates (including RI) are found to have more ""intense"" near center convection and more asymmetric distributions of precipitation prior to intensification onset (but also a greater overall areal coverage). The rate of symmetrization prior to and during intensification increases with increasing intensity change, and rapidly intensifying storms are more symmetric than slowly intensifying storms after onset. While results clearly demonstrate important contributions from intense convection, it is concluded that hot towers, alone, are neither a necessary nor sufficient condition for RI. Of possibly greater importance, intensification is more strongly correlated to the evolution of the areal, radial, and symmetric distribution of precipitation. In addition, while intensification is sensitive to changes in environmental characteristics, these variables, alone, do not consistently offer predictive value in distinguishing 24-hour intensity changes in 10-kt increments (hence the emphasis on convective and precipitation characteristics). |
