GRAPES_Meso模式中两种双参数云微物理方案对冷云过程模拟的比较研究

Comparison of two double-moment cloud microphysics schemes in the GRAPES_Meso model on simulating a cold cloud process

基于GEAPES_Meso模式,分别利用Morrison方案和WDM6方案对2017年1月5—7日一次以层状云为占主导的云系中冷云过程进行模拟和对比分析,评估两种云微物理方案对本次冷云过程云微物理及云辐射过程演变的影响。结果表明:包含丰富暖云和冷云物理过程的Morrison双参数云微物理方案模拟效果优于WDM6方案。Morrison方案模拟的云水路径、云冰有效半径及云光学厚度均大于WDM6方案的模拟结果,而模拟云水有效半径小于WDM6的模拟结果。Morrison方案较WDM6方案对云水(云冰)有效半径、云光学厚度、云水路径及地表短波辐射的水平分布模拟结果更为准确。由于Morrison方案模拟云水有效半径大于WDM6方案,云冰有效半径小于WDM6方案,导致Morrison方案模拟的云水和雪混合比大于WDM6方案模拟结果,而雨水、云冰和霰的混合比则明显小于WDM6方案。相较于WDM6方案,Morrison方案模拟的地表短波辐射水平分布和量值一致性更接近于CERES卫星结果。两种方案中包含的不同微物理过程将影响潜热和感热过程,其中,Morrison方案模拟海平面温度和辐射通量小于WDM6方案,该差异在陆地区域更显著。

A cold cloud system dominated by stratoclouds from January 5 to 7, 2017 is simulated by the GRAPES_Meso model using two cloud microphysics schemes(Morrison and WDM6) to investigate the impacts of different cloud microphysical schemes on the cloud microphysical process and cloud radiation process. The results indicate that the performance of Morrison double-moment cloud microphysics scheme including the warm and cold cloud physical processes is better than the WDM6 scheme. The simulated cloud water path, effective radius of cloud ice and cloud optical thickness by the Morrison scheme are larger than those by the WDM6 scheme, while the simulated effective radius of cloud water by Morrison is smaller than WDM6. The Morrison scheme is more accurate than WDM6 for simulating the effective radius of cloud water(cloud ice), cloud optical thickness, cloud water path, and the horizontal distribution of shortwave radiation on the ground. The effective radius of cloud water(cloud ice) simulated by the Morrison scheme is larger(smaller) than that by the WDM6 scheme.This leads to that the ratio of cloud water and snow simulated by the Morrison scheme is larger than that by the WDM6 scheme, while the ratio of rainwater and cloud ice and hail simulated by Morrison is obviously smaller than that by WDM6. The shortwave radiation simulated by the Morrison scheme is smaller than that by the WDM6 scheme, more consistent with the CERES satellite retrievals. The different microphysical processes represented in the two schemes also affect the processes for latent and sensible heat at the surface, which results in that the simulated sea level temperature and radiative flux with the Morrison scheme are smaller than those with the WDM6 scheme. These impacts of the two different schemes are significantly greater over the land than over the ocean.