华南大气热源和水汽汇的时间变化

用１９８０—１９８６年的ＥＣＭＷＦ资料以及降水量资料，分析了华南地区的大气热源及水汽汇的时空分布变化特征及其与降水异常的联系。分析表明，７年平均的整层积分热源强度在夏半年较强，其中以６，８月最明显，冬季则较弱；辐射冷却在２—４月最显著；水汽汇在２—６月最强，８—１０月次之，其他月份较弱甚至为弱的水汽源。时空剖面反映出热源、水汽汇有明显的季节变化特征，从１月到４月初，大气中层及近地层为热源，而４００ｈＰａ以下为水汽汇；从４月中开始，热源中心逐步抬升到中高层，强度增大，５—６月整个对流层为热源和水汽汇控制，水汽汇中心在低层；经过７月份减弱后，热源和水汽汇又开始增强并维持至９月初，随后，热源、水汽汇中心开始分别下、上移并趋向同层，强度减小。另外，降水显著偏多会伴随热源及水汽汇强度的明显增大。

TIME VARIATIONS OF ATMOSPHERIC HEAT SOURCES AND MOISTURE SINKS OVER THE SOUTH CHINA REGION

The time variations of heat sources Q1 and moisture sinks Q2, and their vertically integrated values (Q1) and (Q2) over South China region and their relations with precipitation anomalies are discussed using ECMWF and rainfall data from 1980 to 1986. There are intense heat sources during the summer half year, especially in June and August, and weak ones in winter seasons. There exist pronounced moisture sinks in two periods from February to June and from August to Octomber. There are positive values of Q1 in the mitldle layer and tile layer near surface while positive values of Q2 exist in the layer below 400hpa from January to early April. After that, the center of Q1 (>O) moves up to a higher level layer with intensified values. During May and June, the heat sources and moisture sinks take over the whole troposphere with lower center of Q2; they would become weak in July and intense again later until early September. After that, the centers of Q1 and Q2 move down and up respectively, to the same middle level with weakening values. In general, the heavier rainfalls are accompanied by intensified heat sources and moisture sinks.