东亚高空急流异常与江淮入梅的关系

使用NCEP/NCAR再分析资料分析了东亚高空急流异常与江淮入梅的关系,得出:东亚高空急流对江淮入梅早、晚有一定的短期预测指示意义。当东亚高空急流偏北时,江淮入梅偏早;反之,当东亚高空急流偏南时,江淮入梅偏晚。东亚高空急流偏北年,西北太平洋海区异常冷,亚欧大陆异常暖,东亚大陆和西太平洋的纬向海陆热力差异由冬到夏的季节转变异常偏早,导致东亚地区大气环流发生季节性转变也偏早;同时,中东太平洋地区ITCZ异常活跃,夏季风系统的推进和副热带高压以及南亚高压的北跳都异常偏早,这种环流有利于江淮梅雨季节开始偏早;高空急流偏南年情况正好相反。

Relationship between East Asia jet anomaly and Meiyu onset over Yangtze-Huaihe River Valley

By using the NCEP/NCAR reanalysis data, the relation between East Asia jet anomaly and Meiyu onset was analyzed. Results show that the East Asia jet plays a certain short-term indicative rale in prediction for the onset time of Meiyu. The earlier Meiyu onset possibly is related to the northwardly East Asia jet, and vice versa. In the northwardly East Asian jet years, the anomalous cold Northwest Pacific, the anomalous warm Eurasia land, and the earlier occurring of their seasonal transition of the zonal sea-land thermal difference promoted the earlier seasonal transition of atmospheric circulation in East Asia. Meanwhile, the significantly active intertropical convergence zone(ITCZ), both the propulsion of summer monsoon system and the northern jump of the Subtropical high and the South Asia high were all favorable for the early Meiyu onset, and vice versa.