Research on Latent Heat Distributions in Tropical Cyclones from Hydrometeor TMI Retrieval Data

The three-dimensional structure of tropical cyclones (TC) and its relationship to intensity changes are statistically examined, using Tropical Rainfall Measuring Mission (TRMM) TMI (TRMM Microwave Imager) retrieval data from 1998 to 2009. A total of 236 TCs over the western North Pacific were observed, providing 1776 "snapshots" of instantaneous TC precipitation. Four types of hydrometeors (precipitable water, precipitable ice, cloud liquid water, cloud ice water) are mainly located around a TC's eyewall areas and the inner edge of the rainbands (<150 km from TC center). During the intensification stage, the hydrometeor contents around TCs are increasing and high-value areas move closer to their center. Maximum hydrometeor content is common at about 50 km from the TC center in its mature stage. The stronger the TC intensity, the closer to the TC center is the maximum hydrometeor content. During the decay stage, the hydrometeor content around the TC decreases and spreads to the outer regions of the TC. There is a close relationship between TC structure and intensity change. The correlations between TC intensity and hydrometeor content over the inner regions (<200 km from TC center) are positive, however, the correlations between TC intensity and hydrometeor content over a TC's outer regions (>200 km from TC center) are negative. Hydrometeor variability seems to occur earlier than changes in the TC intensity. The hydrometeor content around the eyewall areas (<50 km from TC center) increases several hours earlier than the rapid intensification of TCs, and decrease several or tens of hours earlier than TC decay.