Brightness Temperature Characteristics Of Inner-core In Western North Pacific Rapid Intensify Tropical Cyclone

• 1、Atmospheric Science School, Lanzhou University, Lanzhou 730000

Abstract：Using passive microwave satellite data from Special Sensor Microwave Imager (SSM/I) and TRMM Microwave Imager (TMI) for Western North Pacific Tropical Cyclone (TC), the brightness temperature characteristics of inner-core were analyzed in different intensity change categories and different intensity change period of Rapid Intensification (RI). In this reaserch, TCs are devided into five intensity categories which are rapid weakening, slow weakening, neutral, slow intensification, and rapid intensification by 24-h intensity changes. The results show that, although the convection in inner-core is strong, the weak scattering signal of 85GHz and 37GHz Polarization Corrected Temperature (PCT) are still the majority. PCT85 below 250K and PCT37 below 270K are mainly located on shear left inner-core regions in rapid intensification TCs comparing with TCs in other intensity change categories, and the difference of 190-225K PCT85 and 260-270K PCT37 area between shear left and shear right in inner-core are obvious. Meanwhile, the 190-225 K, 225-250 K PCT85, and 260-270K PCT37 areas are less than 30%, 50%, and 60% of total inner-core region before RI onset. After RI onset, brightness temperature will be around TC center, forming more symmetrical. The frequency of minimum PCT85 below 190K and minimum PCT37 below 250K inside inner-core indicate that the occurance frequency of strong convection inside inner-core in RI is higher than that of other intensity categories, and most strong convection occurs 12 hours before RI onset.

Keywords： tropical cylone rapid intensification brightness temperature inner-core convection