The Cloud-Resolving Model Simulation And Sensitivity Experiment Of A Heavy Rainfall Process Over South China

Microphysical processes provide us a unique angle to have a better study of the mechanism and development process of heavy rains, which is more than just having a relationship with large-scale phenomenon. In this paper, heavy rainfall event occurred in 10-15 June 2008 in southern China is simulated with a two-dimensional cloud-resolving model. Besides, sensitivity experiment of cloud radiation is designed to be compared with control-experiment to show the results.Convective domain mean rain rate is larger than that of stratiform in control experiment. In onset phase, domain mean rain rate is small;in mature phase, domain mean rain rate reaches maximum; in decay phase domain mean rain rate is decreased mainly because the rainfall development process is depressed by the decreasing of vapor convergence rate and increasing of local vapor content. In raining stratiform regions, rainfall is mainly from vapor convergence and vapor sink is mainly from local vapor increasing. In convective regions, vapor convergence and local atmospheric drying are the major source for rainfall. Local hydrometeor gain is the major vapor sink. Feature of heat budget is that heat divergence and domain mean latent heat release are the main contributors to domain mean temperature change. Domain mean local atmospheric cooling reaches maximum in mature phase, and local atmosphere temperature change rate is relatively small in onset phase and decay phase. Local mean atmospheric cooling is mainly from stratiform regions (raining stratiform regions and non-raining stratiform regions). Latent heat release in convective regions is consistently large than that of raining stratiform regions, which plays an important role in enhancing local mean latent heat release. Domain mean heat divergence is mainly from raining stratiform regions and convective regions.Rainfall characteristics of the cloud radiation sensitivity experiment is that domain mean vapor convergence rate is decreased, but vapor source is increased by local atmospheric drying and local hydrometeor loss, as a result, the domain mean rain rate is larger than that in control experiment. Local atmospheric drying and local hydrometeor loss reach maximum in mature phase. In raining stratiform regions and convective regions, rain rate is generally increased in convective regions, which rainfall source is mainly from local hydrometeor loss, namely local atmospheric drying. Rain rate is generally decreased in raining stratiform regions, and the major reason is vapor convergence rate is depressed. Increasing of convective rain rate is more than decreasing of raining stratiform rain rate, therefore domain rain rate is enhanced in the sensitivity experiment of cloud radiation. Feature of heat budgets of cloud radiation sensitivity experiment is that local mean atmosphere cooling is increasing in onset phase. Domain mean local atmospheric cooling rate in mature phase is larger than that in onset phase, and local temperature is mainly affected by radiative cooling and decreasing of latent heat release. In decay phase, mean radiative cooling rate is still increasing, and the magnitude of mean latent heat release rate is one degree smaller than that in mature phase, mean heat divergence rate is smaller than that in mature phase.