MM5和WRF对中国东部地区冬季边界层模拟效果比较

Comparison of Simulations on Winter Sounding Profiles in PBL in East China between WRF and MM5

应用MM5和WRF模式对2006年和2007年12月中国东部地区边界层气象要素进行了逐日模拟,利用地面常规观测资料及南京和安庆逐日探空资料对两个模式模拟的地面及边界层内气象要素进行了客观评估与比较。结果表明:MM5和WRF模式模拟的地面温度和相对湿度均较理想,风速效果略差;两个模式模拟的温、湿、风效果均是白天优于夜间;根据观测与模拟的相关性,对温度的模拟效果东部优于西部,相对湿度的模拟效果由东南向西北变差,风速模拟效果平原优于丘陵和山区。总体上,WRF模式对地面温度和湿度的模拟效果均优于MM5模式。以南京、安庆两站为例的边界层内气象要素模拟效果评估结果表明:MM5和WRF模式模拟的150 m以上边界层内温、风、湿廓线均较可信,150 m以下的效果略差,20:00比08:00(北京时)模拟效果好;总体上,WRF模式对温度和湿度的模拟效果较好,而MM5模式对风速模拟效果稍好;两个模式均能再现近地层逆温,都有高估逆温频率的倾向。

MM5 and WRF were run daily for December of 2006 and December of 2007 and the results at ground level and in PBL were assessed and compared by calculating a set of common used statistics measures using the ground-level observations of the China Meteorology Agency routine meteorological network,and the high resolution sounding data at observatories of Nanjing and Anqing. Generally,the simulated ground level temperature and humidity by both MM5 and WRF were reliable,but the simulated wind speed was a little worse. Both models performed better during daytime than during nighttime. In addition,the validation results show ed evident regional distribution,e. g.,the results changed worse from east to west for temperature,from southeast to northwest for humidity,from plain area to hill and mountain areas for wind speed. According to correlation coefficient(R) and mean absolute error(MAE),WRF performed better than MM5 for temperature and humidity at the ground level. Taking Nanjing and Anqing for examples,the modeled sounding in PBL at both 08: 00 and 20: 00 were acceptable,except for the wind speed below 150 m in Nanjing. The results at 20: 00 were better than those at 08: 00,and improved with increasing height for both models. In general,WRF performed better for temperature and humidity,while MM5 performed better for wind speed. Both models could reproduce the near surface temperature inversion,with overestimated the occurring frequency. For the near surface temperature inversion,M M5 outperformed WRF for the frequency,while WRF outperformed MM5 for the thickness and intensity.