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《Acta Scientiarum Naturalium Universitatis Pekinensis》 2007-05
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Climatic Background of Warm-Season Convective Weather in North China Based on the NCEP Analysis

ZHENG Yongguang 1)ZHANG Chunxi 2)CHEN Jiong 1),4)CHEN Mingxuan 3)WANG Yingchun 3)(1)National Meteorological Center of China Meteorological Administration,Beijing,100081; 2)Department of Atmospheric Sciences,School of Physics,Peking University,Beijing,100871; 3)Institute of Urban Meteorology,CMA,Beijing,100089)  
Due to the demand of nowcasting of convective weather in North China(including Beijing,Tianjin,and Hebei Province),the authors use the averaged fields of NCEP 1°× 1° final analyses during May to August of 2000-2005 to analyze the climatic background of convective weather in warm season in north China.The averaged fields include mean circulation of the lower and upper troposphere,mean humidity,temperature,pseudo-equivalent potential temperature,convective available potential energy(CAPE),convective inhibition(CIN),and so on.The results show that the climatic background in May and June is different to that in July and August.In May and June,cold air mass from north is more active,and North China is mainly influenced by disturbances of westerly wind systems in mid-latitudes,in contrast,in July and August this area is influenced by both disturbances of westerly wind systems in mid-latitudes and disturbances in lower latitudes.There are more hailstorms and thunderstorms in May and June,but more heavy rains in July and August.The mean daily variation of relative humidity of lower troposphere reveals that there is one dry line(dew point front)in the afternoon to the east of Beijing,and the averaged streamlines of 850 hPa indicate that there exists a large-scale convergence line in boundary layer at the north of Beijing.The above results provide nowcasting of convective weather in north China with a climatic background.
【Fund】: 国家重点基础研究发展计划(2004CB418300);; 国家自然科学基金(40305004);; “十五”国家科技攻关计划课题“奥运气象保障技术研究”(2002BA904B05);; “十五”国家科技攻关计划课题奥运科技专项“北京奥运会国际天气预报示范计划关键技术研究”(2003BA904B08);; 北京市重大科技计划“奥运会气象保障科学技术试验与研究”(H020620190091)资助项目
【CateGory Index】: P442
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