Microphysical and Kinematic Structure of Convective-Scale Elements in the Inner Rainband of Typhoon Matmo (2014) After Landfall

Abstract

The detailed microphysical structure and processes associated with the kinematic structure of the inner rainband of Typhoon Matmo (2014) over East China were examined using observations from an S band polarimetric Doppler radar and an S band Doppler radar. The kinematic structure of convective cells within the inland inner rainband was similar to that of the principal rainband over the ocean in terms of both updrafts and downdrafts. The hydrometeors within convective regions above the freezing level presented a layered pattern, with ice crystals at the top, dry snow in the middle, and graupel at the bottom just above the freezing level. Dry snow and graupel particles were mainly distributed downwind in relation to the overturning updraft. Heavy rainfall occurred mostly in the updraft region and the region affected by graupel. To further investigate the formation of heavy rainfall, variations in reflectivity, differential reflectivity, and rainwater content within different layers were examined. Two distinct mechanisms were identified: (1) in the updraft region the heavy rainfall was predominantly produced through warm-rain processes of autoconversion, accretion, and coalescence between 0.5 and 5 km in altitude; and (2) outside the updraft region, the heavy rainfall was mainly produced through melting of graupel particles. Evaporation was also observed within the radial inflow layer, most likely due to the cool dry air transported by the low-level downdraft. This study revealed, for the first time, the interactions between the microphysical and kinematic structure and the vertical evolution of warm-rain processes in the inner rainbands of tropical cyclones after landfall.