【摘要】 文中诊断分析了华北汛期降水与亚洲季风区环流异常以及低纬地区热源异常的关系,结果表明:在华北汛期干旱年,亚洲季风偏弱,而在华北汛期降水偏多年,亚洲季风较强,并巳存在两个明显的变化中心,一个位于印度半岛中北部地区,另一个位于菲律宾群岛附近。华北汛期干旱年上述两个地区的热源偏弱,而降水偏多年则偏强。 华北地区干旱年和降水偏多年的前期亚洲季风区热源就已存在明显的不同:华北汛期干旱年前期,亚洲季风区的热源偏弱且位置偏南,表现出季节变化推迟的趋势;华北汛期降水偏多年前期,亚洲季风区的热源偏强且位置偏北,表现出季节变化提早的趋势。 利用IAP L9R15 AGCM气候数值模式,进一步研究了亚洲季风区凝结潜热加热异常对大气环流和华北地区降水的影响,结果表明,印度半岛中北部地区和菲律宾附近地区的凝结潜热加热异常将引起青藏高压和西太平洋副高的异常变化,进而影响到华北地区的降水。更多还原

【Abstract】 Using monthly data of NCEP/NCAR and rainfall of China, the North China rainfall relationships with the circulation anomalies and the heat source over the Asian monsoon area were investigated. The results indicate that the Asian summer monsoon is weaker in drought years of North China, but stronger in flood years of North China. There are two centers of change, one over middle and north India Peninsula, and the other near the Phillipines. There are also obvious changes of corresponding heat source over the Asian monsoon area. Over the two areas, the heat sources are weaker in drought years, but stronger in flood years of North China.There have been obvious differences of heat source in earlier months in drought years or more rainfall years over North China. In drought years, the heat source and the moisture sink are weaker and located to south, showing a delay seasonal change. In more rainfall years, they are stronger and located to north,showing a preceding seasonal change.By using the IAP L9R15 AGCM model, the influences of latent heat anomalies are further examined. It is explored that the latent heat anomalies over the middle and north India Peninsula and Phillipines influence the rainfall of North China through the West Pacific subtropical high and Tibetan high.更多还原