云微物理方案对一次高原切变线暴雨过程数值模拟的影响

Impact of cloud microphysical schemes on numerical simulation of a plateau shear line rainstorm event

利用中尺度数值模式WRF v3.8.1中的16种云微物理参数化方案,对2014年8月26—27日川渝地区的1次高原切变线主导下的暴雨过程进行了数值模拟对比实验.结果表明:WRF模式能够较好地模拟本次切变线强降水过程,总体来说NSSL2-moment方案的模拟效果最好.但不同云微物理方案对于不同量级降水的模拟各有优势,NSSL 2-moment方案对大雨及暴雨的模拟效果最好.在主要降水区,各方案模拟的逐小时降水量的峰值均滞后于实况并且突发性更强,NSSL2-moment+CCN方案在此区域模拟的累积降水量与实况最为接近.云中水成物含量的模拟结果显示,模拟降水较多的方案中其雪粒子含量也较多,而雪粒子不仅在其凝结过程中的潜热释放有利于对流活动发展,并且亦可以通过融化过程促进降水.而对于暖云降水部分,能够到达地面的雨水粒子含量的模拟在各方案中并无显著差异.

Based on 16 kinds of cloud microphysical parameterization schemes in the mesoscale WRF v3.8.1 model, a comparative experiment of a rainstorm event caused by the plateau shear line within August 26th and 27th, 2014 was conducted. The results show that the WRF model successfully simulates this rainstorm process and that the NSSL 2-moment scheme works best in the simulation of this process in general. However, in the simulation of various levels of precipitation, different cloud microphysical parameterization schemes have their own advantages, and the NSSL 2-moment scheme has the best simulation results concerning the heavy rain and the rainstorm. In the main rainfall area, the simulated peak of hourly precipitation lags behind the observations in all kinds of schemes, showing a stronger emergent trend, while the accumulative precipitation simulated by the NSSL 2-moment+CCN scheme is closest to the observations in this area. Simulated results of hydrometeors reveal that snow particle content increases with the rise of precipitation, and the snow particles can not only help the development of convective activities through the release of latent heat during the condensation process, but also promote precipitation through the melting process. As for warm cloud precipitation, there is no significant difference in the content of rain water particles which can reach the ground in each scheme.