Noah-MP陆面模式在华北区域数值预报应用的个例分析

Application of Noah-MP in Numerical Forecast in North China:case study

目前华北区域实际应用的快速更新多尺度分析和短期预报系统(RMAPS-ST)耦合的陆面模式是Noah,Noah-MP是在Noah基础上发展的一种多物理过程陆面模式,其在RMAPS-ST中的应用效果值得深入探究。选取晴天、多云、降雪、降雨天气个例,在华北区域展开数值试验及分析,结果表明:(1)Noah-MP陆面模式相较Noah陆面模式在RMAPS-ST中有一定的应用优势,其对风速预报性能的改进比气温、比湿显著;(2)Noah-MP陆面模式的应用对晴天的气温、降雪天气的比湿以及多云天气的风速预报性能改进较显著,其中多云天气风速的预报准确率可提高约50.43%;(3)Noah-MP陆面模式的应用对气温预报性能的改进主要集中在山西中南部、河北中南部以及山东地区,对比湿预报性能的改进主要集中在山西中北部、河北北部,对风速预报性能的改进主要集中在山地附近;(4)Noah-MP陆面模式中冠层辐射传输、径流及地下水物理过程对北京地区比湿、风速的预报结果影响不显著,而湍流输送过程选择Chen97方案、径流及地下水过程选择SIMGM方案对地表能量通量模拟效果较优,且对气温的预报性能较好。

Noah land surface model is applied in the Rapid-refresh Multi-scale Analysis and Prediction System-Short Term(RMAPS-ST)that is used for the numerical forecast for North China.Noah-MP is a land surface model with multi-physical processes based on Noah.It is worthwhile to investigate how well Noah-MP can be applied in the RMAPS-ST.Therefore,we selected individual case of sunny,cloudy,snowy,and rainy days to conduct numerical experiments and mechanism analysis in North China.The results are shown below.(1)Compared with Noah,Noah-MP has some advantages in the RMAPS-ST.The improvement of wind speed forecast in North China is more significantly than that of air temperature and specific humidity by applying Noah-MP land surface model.(2)The application of Noah-MP has more obvi⁃ous improvement in the forecast performance of air temperature on sunny days,specific humidity during snowfall,and wind speed on cloudy days.The forecast accuracy of wind speed on cloudy days is increased by about 50.43%.(3)The application of Noah-MP has improved air temperature forecast mainly in the middle and south of Shanxi Province,the middle and south of Hebei Province,and Shandong Province.The improvement of specific humidity forecast is mainly concentrated in the middle and north of Shanxi Province and the north of Hebei Province.The improvement of wind speed forecast is mainly concentrated in the vicinity of mountains.(4)For Beijing,Noah-MP with Chen97 option for surface layer drag coefficient(SFC)and SIMGM option for runoff and groundwater(RUN)has a better effect on the simula⁃tion of surface energy fluxes and air temperature,while the options for radiation transfer(RAD),runoff and groundwater(RUN)do not have a significant effect on the forecast results of specific humidity and wind speed.