摘要
[ Objective] The aim was to analyze the regional rainstorm in Hunan from August 5 to 6 in 2011. [ Method] Based on regional automatic station data, air-exploration data, upper air data and radar data in Hunan Province, the formation mechanism of rainstorm in Hunan was analyzed. The changes of reflection rate, horizontal speed and relevant physical quantity factors in Dongting Lake were explored, and the reports of height field and wind pattern in Europe center were testified. [ Result] Dudng this process, the regional rainstorm occurred when the typhoon influenced east coast. The coastal circulation background was a two-ridge-one-trough situation. The leading influential system was the lower trough in the up- per air, shear line in the middle and lower layer and ground weak cold air. There was bypass at 200 hPa. CAPE value enlarged and SI index de- creased. Enough vapors can make up the transportation of water vapor in the middle and lower layer. Two echo clouds entered strong convection wind storm, and dry air entered into the storm, which resulted in slowly movement of strong wind storm. There was back wind area and strong con- vergence area in the lower layer. Heedwind and strong convergence areas were in the lower layer of speed product. By comparing the report of 500 hPa height with the reality, it was found that the height value of the typhoon was higher than the reality, the high pressure center was smaller than the reality, 48 h forecast showed more mistakes than the 24 h report. The UV report at 500 and 800 hPa was larger than that at 24 h. The error in report typhoon was large, especially around the shear line or trough line. [ Conclusion] The study provided reference for the forecast of rainstorm.
[ Objective] The aim was to analyze the regional rainstorm in Hunan from August 5 to 6 in 2011. [ Method] Based on regional automatic station data, air-exploration data, upper air data and radar data in Hunan Province, the formation mechanism of rainstorm in Hunan was analyzed. The changes of reflection rate, horizontal speed and relevant physical quantity factors in Dongting Lake were explored, and the reports of height field and wind pattern in Europe center were testified. [ Result] Dudng this process, the regional rainstorm occurred when the typhoon influenced east coast. The coastal circulation background was a two-ridge-one-trough situation. The leading influential system was the lower trough in the up- per air, shear line in the middle and lower layer and ground weak cold air. There was bypass at 200 hPa. CAPE value enlarged and SI index de- creased. Enough vapors can make up the transportation of water vapor in the middle and lower layer. Two echo clouds entered strong convection wind storm, and dry air entered into the storm, which resulted in slowly movement of strong wind storm. There was back wind area and strong con- vergence area in the lower layer. Heedwind and strong convergence areas were in the lower layer of speed product. By comparing the report of 500 hPa height with the reality, it was found that the height value of the typhoon was higher than the reality, the high pressure center was smaller than the reality, 48 h forecast showed more mistakes than the 24 h report. The UV report at 500 and 800 hPa was larger than that at 24 h. The error in report typhoon was large, especially around the shear line or trough line. [ Conclusion] The study provided reference for the forecast of rainstorm.
基金
Supported by Reporter Program of China Meteorological Administrator ( CMAYBY2012-037)
