Numerical Study Of Deep Convective Anvil’s Hydrometeor Source And Its Microphysical Characterization

Cloud plays an important and significant role in earth climate system. Cloud can influence global climate change in virtual ways such as affecting global radiation balance because of cloud’s radiation effects and global water cycling because of hydrometeor in cloud. As a result, cloud plays dominant roles in climate change because of change of global radiation balance and global water cycling. Cirrus and anvil occupy70%acreage of tropical area, and they all contain a large number of solid type hydrometeor particles such as snow, grapuel, and hail which can influence radiation balance through their special radiation effects. In a word, cirrus and anvil have impacts on climate change with their radiation adjusting.This paper conducts numerical simulation of an deep convection progress during TWP-ICE with high resolution four-nested WRFV3.4.1model, horizontal grid space of the forth nest of WRF model is0.667km, which can resolve the single convective system explicitly. With FLEXPART Lagrangian transport and dispersion model, this paper also uses the WRF simulation data outputted every five minutes to analyze the trajectories of convective system’s transportation. By analysis, the paper comes to following conclusion:Firstly, high resolution WRF models, especially those with horizontal grid space less than lkm (-0.667km) can be used to simulate cloud resolve scale system. A comparison of WRF simulation results with observation and multi-CRM simulation results shows that high resolution WRF model reproduces the variation character of cloud during TWP-ICE.Secondly, with analyzing of character of Lagrangian transportation of convective hydrometeors and convective updraft mass flux, this paper finds that unlike most convective parameterizations assumption based on mass flux, updraft mass flux decrease with height and hydrometeor has been transported to convective system outside. This conclusion is more agreeable with actual condition and most convective parameterizations assumption may overestimate the contribution percentage of high troposphere moisture from convective system. Thirdly, analyses of character of convective system’s transportation with FLEXPART Lagrangian model show2hours after transported, convective hydrometeor are transported to levels about13km, and the environmental specific humidity, air density, and air temperature is0.7g/kg,0.3kg/m3and-54℃, respectively. After transported to13km, hydrometeor is transported mainly in horizontal direction, and hydrometeor with higher initial height can be transported in a long distance in shorted time.Finally, analyses of trajectories of hydrometeor transportation in convective system show that hydrometeor’s transportation trajectories are mainly along environmental steering current, and the furthest distance hydrometeor can be transported is200-300km and anvil area about50-150km are affected most by hydrometeor transportation. Estimation analyses show that time scale of impacts of hydrometeor from convective system on anvil formation is4-6hours, and about10～20%hydrometeor from convective system contributes to the formation and development of anvil. For those hydrometeor from lower initial level, because of low level environmental disturbance, a small number of hydrometeor can be transported to upstream of convective system (opposite to environmental steering current).