Analysis on the effects of different horizontal resolutions and microphysical schemes on the simulation of a rainstorm in central China

Abstract

Using the Weather Research and Forecasting (WRF) model, a heavy rainfall in central China during 30 June to 1 Jul 2016 is simulated to explore the effects of different horizontal resolutions and microphysical schemes. The results show that:(1) all of the simulations can reproduce the rainfall well, but simulated rainstorm areas are smaller than observations. The total rainfall is more sensitive to horizontal resolutions than to microphysical schemes, although the big rainstorm is sensitive to both horizontal resolutions and microphysical schemes. With different horizontal resolutions, microphysical schemes and cumulus schemes affect the performance of the rainfall forecast in common. TS scores of 24-hour accumulated precipitation show that the simulation with 12 km horizontal resolution andthe Lin scheme performs the best in extremely rainstorm simulation. (2) The evolution of hydrometeors simulated by different microphysical schemes largely depends on themselves. The Lin scheme simulates more ice and graupel, but less snow. The Thompson scheme simulates more snow, but less ice and graupel. The Morrison shceme simulates the similar contents among three types of ice hydrometeors. The Lin scheme underestimates the ice-water content significantly. The Thompson and Morrison scheme overestimate the ice-water content significantly. (3) Updraft strength simulated by different schemes affects the distribution of hydrometeors in the mature stage. The Lin scheme simulates upright updraft and weak upper flow so that most of the ice hydrometeors are limited in convective system. The Thompson and Morrison schemes simulate slantwise updraft and strong upper flow so that most of ice hydrometeors flow with upper flow.

Keywords

• wrf
• horizontal resolution
• microphysical scheme
• ice hydrometeor