Simulation And Analysis Of Heavy Precipitation Using Cloud Microphysical Scheme Coupled With High-resolution GRAPES Model

In this study, two heavy precipitation processes are simulated using the two-moment cloud microphysical scheme coupled with high-resolution GRAPES model. The scheme is compared with WSM6 scheme, NCEP5 scheme and a variety of observation data to diagnose the prediction performance and analyze the key cloud microphysics process in deep convective precipitation. The simulation study shows that:The results derived from the two-moment scheme fit better with observations on rain belt direction, precipitation range and intensity, which also has obvious advantages on the maximum echo height and strength of convective clouds, the distribution of ice content and the cloud anvil structure. However, the ice content and echo height are slightly lower than observations. The WSM6 scheme can also simulate the direction and range of the rain belt, but the precipitation intensity is significantly stronger, and the configuration between hydrometeors and surface precipitation is unreasonable. At the same time, the ice content and echo height are lower than the observations, and the location of strong echo are not accurate enough. All these results will provide meaningful support for the improvement of microphysical schemes.Two precipitation processes are constituted by stratiform cloud precipitation and convection cloud precipitation embedded in the former. Ice phase particles especially graupel particles play a leading role on the convection and precipitation in the strong convection clouds and the melting of graupel is the main source of strong precipitation, while graupel distribute rarely in the stratiform precipitation region which is mainly affected by the melting of snow and warm cloud precipitation. Besides, adequate updraft contribute to the sufficient growth of graupel, and the lack of graupel can not accurately simulate the position and intensity of heavy precipitation center.Latent heat of phase change has an important feedback effects on on the dynamic and thermodynamic structure of the model. The growth of hydrometeors can release latent heat, which can promote the continuous development of updraft and convection, and the rise of temperature. when the particle size is large enough, hydrometeors will melt and fall to the ground, corresponding with the decrease of temperature and the increase of surface precipitation. Without considering the release of latent heat, the surface precipitation will be greatly suppressed.