Effects of Latent Heat Release from Single-Moment and Double-Moment Microphysical Schemes on the Simulated Intensity of Typhoon Songda

Abstract

This study aims to quantify the magnitude of latent heat release by strong typhoons in the Northwest Pacific region and to identify the key cloud microphysical processes that affect the release of latent heat. The Weather Research and Forecasting mesoscale numerical model was used to simulate Typhoon Songda from 2011. Single- and double-moment 6-class (WSM6 and WDM6) cloud microphysics schemes were used to simulate the 3D structure and evolution of latent heat release. Simulations show that condensation of cloud water is the main source of latent heat release, while the main sources of latent heat absorption are evaporation of rain and cloud water. Depositional heating in cold cloud processes in the upper troposphere also plays an important role in the evolution of typhoon intensity. Latent heat release and absorption simulated by both schemes evolve through the phases of intensifying, maintaining, and weakening during the lifetime of the typhoon. The largest latent heat release occurs at altitudes between 5 and 10 km; condensational heating plays a major role at altitudes below 6 km, while depositional heating is the dominant process at altitudes from 6 to 12 km. Compared with WSM6, the WDM6 scheme produces smaller absolute values of latent heating from condensation and evaporation of cloud water and a more reasonable vertical distribution of cloud water mixing ratio. Positive latent heating from WDM6 is larger than that from WSM6. However, because of stronger processes of evaporation of rainwater and sublimation of cloud ice, total net latent heat release is lower in WDM6, and hence, simulated typhoon intensity is higher in WSM6.