摘要
利用江苏省24个国家站降水、日照时数观测资料,以及NCEP/NCAR再分析资料、海温指数、HadISST全球海表温度资料,采用EOF分析、合成分析等方法,分析了1961-2019年江苏省冬季连阴雨(雪)出现次数全省一致偏多年份的异常环流特征及其成因。结果表明:江苏省冬季连阴雨(雪)出现次数的空间分布主要为全省一致型和南北相异型,前者为主要模态。连阴雨(雪)出现次数全省一致偏多型年份,中高纬高层欧亚地区上空环流形势为“+-+”分布型,位于青藏高原北部高压脊以及东亚大槽和欧洲东部低压槽均较常年偏弱。低层位于欧亚地区中部的冷高压较常年偏弱,导致冷空气势力偏弱。中低纬低层西太平洋(菲律宾附近)存在异常反气旋环流,其西部的异常偏南气流加强了水汽的向北输送,冷暖气流在30°N交汇抬升,为江苏省连阴雨(雪)天气过程提供了有利的水汽条件和抬升条件。当中部型El Nino事件发生时.Walker环流在西太平洋的异常下沉气流会激发出异常反气旋,使得东亚冬季风减弱,向北水汽输送加强,导致江苏省一致偏多型连阴雨(雪)天气的发生。
Based on daily precipitation and sunshine duration data of 24 national meteorological stations in Jiangsu province from 1961 to 2019, sea surface temperature(SST) indices and HadISST monthly mean SST data, the anomalous circulation characteristics and causes for continuous winter rain(snow) in Jiangsu province were analyzed using the empirical orthogonal function(EOF) analysis and composite method. The analysis revealed that the spatial distribution of the continuous rain(snow) during winter in Jiangsu from 1961 to 2019 mainly exhibited provincially uniform pattern and north-south dissimilarity pattern. In the years of frequent uniform-type continuous rain(snow), the circulation form of the middle-and high-latitudes presented a “+-+” pattern from east to west in Eurasia at high levels, implying that the northern ridge of the Tibet Plateau, East Asian Trough, and Eastern European Trough were weak. At low levels, central Eurasia showed a negative anomaly field, implying that the Asian cold high was weak. Further, the circulation pattern in the middle and high latitudes indicated that the cold air force was weak. An anomalous low level anticyclonic circulation over the western Pacific Ocean was observed at the middle and low latitudes. The anomalous southward current at the west anomalous anticyclonic circulation strengthened the northward transport of water vapor. Moreover, the cold and warm currents met around 30°N, providing favorable water vapor and lifting conditions for continuous winter rain(snow) in Jiangsu province. When the CP El Nino event occurred, the sinking current of the Walker circulation in the western Pacific triggered the abnormal anticyclone, which weakened the East Asian winter monsoon and strengthened the northward transport of water vapor to Jiangsu, producing continuous winter rain(snow) in Jiangsu province.
作者
吴冬梅
袁良
王裕萍
阮博
张霞琴
Wu Dongmei;Yuan Liang;Wang Yuping;Ruan Bo;Zhang Xiaqin(Xiangcheng Meteorological Burea,Suzhou 215132,China;Xiangyang Meteorological Burea,Xiangyang 441000,China)
出处
《气象与减灾研究》
2022年第2期83-91,共9页
Meteorology and Disaster Reduction Research
基金
江苏省气象局预报员专项(编号JSYBY202008).
关键词
冬季连阴雨(雪)
时空分布
大气环流
海温异常
EOF分析
continuous winter rain(snow)
spatial and temporal distribution
atmospheric circulation
SST anomaly
EOF a-nalysis
