不同边界层方案对一次浙江海雾数值模拟的敏感性研究

Sensitivity of an advection fog process numerical simulation to different boundary layer parameterization schemes over Zhejiang coastal area

通过欧州中期天气预报中心大气再分析资料ERA5资料驱动WRF模式,对2019年6月4—6日发生于浙江沿海的一次平流雾过程开展模拟实验,并利用浙江省气象自动站逐小时气象观测数据检验4种边界层参数化方案(YSU、QNSE、ACM2、MYJ)的模拟能力。结果表明:从对地面气象要素的检验来看,各边界层方案整体对气温和相对湿度的模拟效果较好,但对风速的模拟均较观测结果存在一定的高估,其中ACM2与YSU方案对相对湿度和风速的预报效果总体好于QNSE与MYJ方案,且ACM2方案在相对湿度的预报平稳度以及误差检验上要优于YSU方案。ACM2方案可以较好地再现此次过程海雾的生消演变及雾区分布;YSU方案预报的雾区范围偏大,存在一定空报;而QNSE与MYJ方案则对海-陆雾区分布的把控能力有限。边界层高度直接反映湍流运动的强度,继而影响海雾的生消与发展。局地闭合模型QNSE与MYJ相较于非局地闭合模型YSU和ACM2对沿海地区的湍流混合强度估计不足,造成了对沿海雾区的一定漏报。

An advection fog process during 4‒6 June 2019 over Zhejiang coastal area is simulated using the WRF model driven by the ERA5 data,and the effects of different boundary layer parameterization schemes(YSU,QNSE,ACM2,MYJ)on the simulation results are studied in comparison with observed meteorological data.The results show that all boundary layer parameterization schemes perform well on simulating surface air temperature and relative humidity,but all of them overestimate surface wind speed.The ACM2 and YSU schemes overall perform better than the QNSE and MYJ schemes on the relative humidity and surface wind speed simulation.The ACM2 scheme exhibits a better capacity than the YSU scheme on the relative humidity prediction stability and error test.The ACM2 scheme generates reasonable temporal evolution and spatial distribution of the fog.The YSU scheme overestimates the fog zone and generates occasional fail forecast.The QNSE and MYJ schemes produce insufficient accuracy in the spatial distribution of sea‒land fog zone.Boundary layer height directly reflects the intensity of turbulent flows,and thus plays a critical role in the evolution of advection fogs.Compared with the YSU and ACM2 schemes,the QNSE and MYJ schemes underestimate the turbulent mixing intensity in coastal areas,resulting in occasional fail forecast of coastal fog zone.