两种微物理方案对夏季东北亚阻塞过程影响的数值模拟结果分析

选用NCEP/NCAR FNL再分析资料，利用中尺度模式WRF对2011年7月25日—8月3日的一次东北亚阻塞高压过程进行数值模拟试验。通过数值对比试验，讨论有冰相物理过程和无冰相物理过程的两种微物理方案对此次阻塞高压过程的强度和维持时间模拟的差异，并简要阐述原因。结果表明:WRF对阻塞高压过程有较好的模拟效果，有冰相物理过程的微物理方案模拟的阻高强度及维持时间较接近实况，整体阻塞闭合环流形势、高压中心值、中心位置以及中心上下游的低压槽强度均与实况接近；无冰相物理过程的微物理方案模拟阻塞高压在500 及200 hPa平均位势高度场上没有闭合的高值中心出现，500 hPa阻塞高压强度弱，持续时间短，200 hPa则相反。进一步研究发现，这两种差异主要由阻塞高压活动区域内的非绝热加热不同引起的，它对阻塞高压形成的强度和维持时间具有很好的指示意义。另外，阻塞高压附近区域的微物理潜热释放对阻塞过程的强度和维持时间也有一定影响。 

Numerical simulations of a summer blocking process in Northeast Asia using two microphysical schemes

The mesoscale model WRF driven by the NCEP/NCAR FNL reanalysis data is used to simulate a blocking process occurred in Northeast Asia during 25 July—3 August 2011. Comparative analysis of numerical experiments with and without ice phase microphysical processes is conducted to discuss the WRF model ability for the simulation of the strength and maintenance time of the blocking process. The results show that the WRF model can well simulate this blocking process. The results using the microphysical scheme with ice phase process show that the simulated blocking intensity and maintenance time are close to observations. The overall blocking pattern with closed circulation, the pressure value at the blocking high center and its location, the strength of the low-pressure trough upstream and downstream of the high pressure center are consistent with actual situation. The simulation using the microphysics scheme without ice-phase process cannot reproduce the closed high pressure contour in the mean geopotential height fields at 500 and 200 hPa. The simulated blocking is weaker in intensity and shorter in duration than observations at 500 hPa, while the opposite is true at 200 hPa. Further study shows that the differences between the two experiments are mainly caused by different diabatic heating in the blocking area, which is a good indicator of the strength and duration of the blocking. In addition, the microphysical latent heat release near the blocking area also affects the strength and maintenance time of the blocking process.