中尺度天气预报模式边界层参数化方案以及近地层方案对苏州东山冬季近地层气象要素模拟的影响

The Effect of Planetary Boundary Layer Parameterization Schemes and Surface Layer Schemes in Mesoscale Weather Research Forecasting model on the Simulation of Surface Layer Meteorological Parameters at Dongshan,Suzhou in Winter

运用WRF3.9模式并选取四种常用的边界层参数化方案(YSU、ACM2、MYJ和BL)和两种近地层方案(Eta和MM5)模拟了2015年1月16~25日苏州东山的近地层气象要素,并与东山气象站观测实验数据进行对比,评估了四种边界层参数化方案对近地层气象要素的模拟能力。同时设置了边界层参数化方案与近地层方案耦合的敏感性试验,分析两类方案的耦合对近地层气象要素模拟的影响。结果表明:①白天四种边界层方案对2m温度的模拟差异较小,两种近地层方案的模拟结果有差异,对流混合较弱时Eta方案模拟较好,对流混合较强时MM5方案较好;夜间四种边界层方案和近地层方案均有影响,但是整个观测期间四种方案的模拟结果统计量差异较小;②无论白天还是夜间,四种边界层参数化方案模拟的2m相对湿度均高于观测值,BL方案的模拟效果最佳,MYJ方案的模拟偏差最大;③无论白天还是夜间,四种边界层参数化方案对10m风速的模拟均存在一定程度的高估,MYJ方案的模拟效果最好,四种方案对风向的模拟均优于对风速的模拟,白天的模拟效果整体优于夜间;④选择不同的近地层方案对风速和风向的模拟结果没有明显影响,对2m气温模拟结果的影响小于对2m相对湿度模拟结果的影响,BL边界层方案与MM5近地层方案耦合对近地层气象要素2m气温和2m相对湿度的模拟效果最好。

Four commonly used planetary boundary layer (PBL) parameterization schemes (YSU,ACM2,MYJ and BL) and two surface layer schemes (Eta and MM5) in WRF3.9 model were used to estimate the surface values of meteorological parameters observed by Dongshan meteorological station in Suzhou city,China,from 16 to 25 January 2015.The simulation results were compared with the observational data,and the simulation ability of surface meteorological parameters by four PBL schemes was evaluated.Meanwhile,the sensitivity test on the four PBL schemes and the coupling with the two surface layer schemes was set.The influence of the coupling of the two types schemes on the simulations were also analyzed.The results reveal that the differences between the simulations of temperature at 2 m level during the daytime using four PBL schemes is negligible.In contrast to that,the results using two different surface layer schemes show large variation.The Eta scheme performs better when convection mixing is weaker,while the MM5 scheme is better when convection mixing is stronger.For the nighttime simulation,the differences between modeling results using different PBL schemes are small throughout the entire observation period.It is also found that the simulate values of relative humidity at 2 m level are all larger than the observed values,and the BL scheme performs the best while MYJ scheme has the largest deviation.The four PBL schemes used in simulations all overestimate wind speed at 10 m level,in which MYJ scheme behaves the best.The simulations of wind direction using these four PBL schemes are found better than those of wind speed,and better in the daytime than in the nighttime.The selection of the two surface layer schemes has no obvious influence on the simulation of wind speed and wind direction at 10 m level,and the selection has a smaller impact on the simulation of temperature at 2 m level than on the simulation of relative humidity at 2 m level.For the simulation of temperature and relative humidity at 2 m level,the coupling of the BL scheme and the MM5 surface layer scheme is found the best.