Diabatic Heating Associated with Different Types of Precipitation during Tropical Cyclone Formation

The spectral latent heating profiles derived from the TRMM PR are examined and compared to diabatic heating profiles from a high-resolution numerical model simulation during tropical cyclone formation. The diabatic heating associated with different types of precipitation (deep convection, congestus, and stratiform precipitation) was examined. The contribution by stratiform precipitation to the upper-level heating is comparable to deep convection, especially before genesis. In particular, the diabatic heating associated with stratiform precipitation contributes to the development of a deep diabatic heating profile, which may aid in generating the warm core in the upper troposphere and reducing the surface pressure. However, a comparison of the model simulations with the TRMM showed that heating rates associated with deep convection were one order of magnitude weaker in TRMM. As a result, the total heating derived from TRMM is more top heavy relative to the model. Furthermore, a comparison between the conditional mean heating profiles derived from the model and TRMM show that the magnitude of the conditional heating rate is also weaker in TRMM relative to the model for all precipitation types, yet both suggest that the conditional heating that occurs above the melting layer in stratiform precipitation is much greater relative to the weak cooling rates below the melting layer and the heating rate by congestus is comparable to that by deep convection prior to genesis. Lastly, large differences in deep convective heating rates between the model and TRMM suggest WRF likely overestimates the frequency of occurrence of deep convection. This study suggests that tropical cyclone formation is an outcome of the collective contribution by different types of precipitation, instead of the result of a few intense, deep convective clouds.