Characteristics of Latent Heating Rate Profiles for Typhoons in 15 Years from TRMM PR L2H25 Data

Latent heat release associated with deep convection within tropical cyclones (TCs) is essential for TC intensification, that is, the latent heat release is the main source to develop the TC inner core. However, the temporal and spatial coverage of TC observation and analysis are limited because TCs develop in the ocean where the in-situ observations are usually scarce. Hence, satellite observations are expected to support to achieve the temporally and spatially homogeneous observations for TCs even when enough in-situ data are not available. Considering this advantage of satellite observations, this study tried to gain the average profiles of the latent-heating rate using 339 TCs which occurred in the western North Pacific basin in 2000–2014 (15 years), focusing on TC intensity, life stage, and so forth. To evaluate the latent-heating rate, JAXA L2H25 (Ver.7) from TRMM PR (Shige et al. 2004, 2007) were used. For discussions considering TC warm core structure, the temperature profile data derived using 55-GHz band observations of the Advanced Microwave Sounding Unit-A (AMSU-A) of NOAA and MetOp satellites (Demuth et al. 2004) were introduced.

This study showed several remarkable aspects of the average latent-heating rate profiles for the TCs. The height of the latent-heating rate maximum tended to be higher for the intensification and mature phases than that for the decay phase. Noticeably, the maximum temperature anomaly near the TC center, which indicates the warm core intensity, tended to be largest around at 11–13 km height during the intensification and mature phases while it appeared below 6 km height during the decay phase. In addition, TCs with the large temperature anomaly near the TC center tended to have larger latent-heating rate within the TC inner core. These results suggest that the latent heat from the deep convection within the TC inner core made an essential role in the warm core development. Further, a large latent-heating rate appearing around at the mid-level for rapidly developed TCs during the intensification phase was notable, which is consistent with the results theoretically derived by using the Rossby-Ertel Potential Vorticity equation.