摘要
Abstract
[ Objective ] The research aimed to study the reason of local heavy rainstorm forecast error in the subtropical high control. [ Method] Started from summarizing the reason of forecast error, by using the conventional ground observation data, the upper air sounding data,T639, T213 and European center (ECMWF) numerical prediction products data, GFS precipitation forecast product of U. S. National Center for Environmental Prediction, the weather situation, physical quantity field in a heavy rainstorm process which happened in the north of Shaoyang at night on August 5, 2010 were fully analyzed. Based on the numerical analysis forecast product data, the reason of heavy rainstorm forecast error in the subtropical high was comprehensively analyzed by using the comparison and analysis method of forecast and actual situation.[ Result] The forecasters didn't deeply analyze the weather situation. On the surface, 500 hPa was controlled by the subtropical high, but there was the weak shear line in 700 and 850 hPa. Moreover, they neglected the influences of weak cold air and easterly wave. The subtropical high quickly weakened, and the system adjustment was too quick. The wind field variation in 850,700 and 500 hPa which was forecasted by ECMWF had the big error with the actual situation and was by east 2 longitudes than the actual situation. In summer forecast, they only considered the intensity and position variation of 500 hPa subtropical high, neglected the middle, low levels and ground situation variations. It was the most key element which caused the rainstorm forecast error in the subtropical high. The forecast error of numerical forecast products on the height field situation variation was big. The precipitation forecasts of Japan FSAS, U.S. National Center for Environmental Prediction GFS, T639 and T213 were all too small. The humidity field forecast value of T639 was small. In the rainstorm forecast, the local rainstorm forecast index method wasn't used in the forecast practice. In the precipitation forecast process, they only paid attention to the score prediction of station and didn't value the non-site prediction. Some important physical quantity factors weren't carefully elaborated. [ Conclusion] The research provided the reference basis for the forecast and early-warning of local heavy rainstorm.关键词
大暴雨/副热带高压/预报失误/原因分析Key words
Heavy rainstorm/ Subtropical high/ Forecast error/ Reason anaiysis分类
天文与地球科学
