Convective and Precipitation Properties of Tropical Cyclone in the Western North Pacific as Observed by TRMM Satellite

Abstract:

The convective properties and three-dimension structure of precipitation in the inner-core (IC), inner rainband (IB), and outer rainband (OB) regions of tropical cyclones (TCs) in the western north Pacific basin have been studied by using the data from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), Microwave Imager (TMI), Lightning Imaging Sensor (LIS) and best-track data during the period from 1998 to 2013. It is found that stratiform precipitation is dominated in all regions of TCs, especially in IB, the proportion of convective precipitation is highest in IC regions and the proportion of stratiform precipitation is highest in IB regions. The highest average precipitation rate of convective precipitation, stratiform precipitation and other precipitation occur in IC regions, and the lowest occur in OB regions. Only 1.1% of all the precipitation features have maximum 20-dBZ radar echo ≥ 14 km, which contribute 24.4% of rainfall and 70.0% of lightning. The precipitation features in IC regions have much stronger radar echoes and ice scattering (i.e. lower 85 GHz PCT) than those in IB and OB regions, which indicates that the strongest convections appear in IC region, and the convection intensity increases as the TC intensity increases. Stronger convective cells also occur in IC regions, but there strength changes little during different TC categories. There is significant difference of flash density of precipitation feature normalized by the raining area in IC and OB regions among different TC categories, and the lowest flash density is always found in IB regions. The flash density in OB features is 1.2 times higher than that in IC features for all TC categories, the flash density in IC features 2.4 times higher than that in OB features for CAT35 TCs, but the flash rate of both precipitation features and convective cells in IC regions is highest except for CAT12 TCs