The effects of boundary layer parameterization schemes on the simulation of a strong warm-sector convective process over South China
Based on the WRF mesoscale numerical model,the effects of four boundary layer parameterization schemes(YSU,MYJ,MYNN,ACM2)on the simulation of a strong warm-sector convection process in South China are compared and analyzed.The results show that:(1)all four schemes can simulate the development of strong convective weather in Guangdong in the afternoon,but the simulated average precipitation is smaller than the actual situation,and the simulated maximum precipitation intensity appears with a time lag of 1～2 hours.(2)The vertical distribution of temperatures simulated by the four schemes are very close to the actual situation.The simulated humidity in the low level below 850 hPa is generally larger,while the simulated wind speeds between 800～950 hPa are small.(3)In contrast,the convective echo pattern simulated by the non-local closure schemes YSU is the closest to the actual situation,while the MYJ scheme is more effective in simulating the wind speeds in the low-level region from 800～950 hPa,and the simulated time of occurrence of heavier precipitation is closer to the actual situation.(4)Although MYJ and MYNN are both local closure schemes,there are significant differences in their simulation results.The simulated low-level wind speeds,surface sensible heat fluxes,and latent heat fluxes of MYNN scheme are significantly smaller than those of the MYJ scheme,while the difference between the simulation results of YSU and ACM2 schemes is relatively small.
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