Effect of the thermodynamic feedback of tropical cyclones on the subtropical high

Abstract

In this study, the thermodynamic feedback effect of excess cloud ice possibly originating from tropical cyclones (TCs) on the western Pacific subtropical high (WPSH) and, in turn, the TC track was investigated by use of sensitivity experiments with the Weather Research and Forecast (WRF) model. The results indicated that excess cloud ice in the area north of the TC track can alter the temperature and the geopotential height there via latent heat release (cooling due to melting and evaporation) of hydrometeors in the upper (lower) troposphere, accompanying by the enhanced local downdrafts. Moreover, under the influence of the changed steering flow, the TC turns northward ahead of time relative to its original track. The sensitivity experiments confirm that the thermodynamic feedback effect of hydrometeors aloft can ultimately affect the TC track, which is also supported by observations of some selected northward-turning TCs.