WRF模式对乌鲁木齐机场一次冻雾天气的数值预报对比试验分析

Contrast Analysis of WRF Model Forecasts on a Freezing Fog Event Occurred at Urumqi Airport

利用WRF模式和GFS资料对2016年11月28—29日乌鲁木齐机场一次冻雾天气过程进行预报,针对不同微物理过程、近地层、陆面过程、边界层等方案设计了13个预报方案组合,并将预报结果与观测资料进行对比分析发现,此次冻雾过程预报中,模式对陆面过程、近地层、边界层等参数化方案组合较为敏感,最优方案组合微物理过程为WDM6、近地层方案为QNSE,陆面过程方案为Noah,边界层方案QNSE。以最优的方案组合预报结果对此次冻雾进行分析,发现利用模式预报的环流形势、层结条件、温湿条件、混合条件等能够很好的判断出此次冻雾过程。就此个例而言,WRF模式预报的机场上空稳定层的变化,湿层结构、风场的水平和垂直结构等,对冻雾的生消以及冻雾过程中的能见度变化有一定的指示意义。

A freezing fog event occurred at Urumqi airport during 28-29 November 2016 is simulated by using WRF model and GFS data, and the simulated results from 13 different combinations of WRF model schemes,such as microphysical schemes,surface-layer schemes,LSM schemes and PBL schemes are compared. Results shows that the simulation are sensitive to different combinations of WRF model schemes. The optimized scheme for this freezing fog simulation is the combination of WDM6 microphysical scheme,QNSE surface-layer scheme,Noah LSM and QNSE PBL. The simulation from this combination shows that the freezing fog event can be well diagnosed by using the forecasted circulation pattern,stratification condition,temperature and relative humidity. In this case,the change of stable stratification above the airport,the horizontal and vertical structure of relative humidity and wind field simulated by WRF model have valuable guidance to the occurrence and dispersion of the freezing fog and the change of visibility.