摘要:本文利用国家气候中心的1961~2016年华北雨季监测资料、美国国家环境预报中心/大气研究中心（NCEP/NCAR）的大气再分析资料、NOAA海表温度资料，分析了华北雨季开始早晚的气候特征，然后利用合成分析、回归分析等方法，研究了华北雨季开始早晚与大气环流系统和关键区域海表温度的关系。结果表明，56 a来华北雨季开始最早在7月6日，最晚在8月10日，1961~2016年华北雨季开始平均日期是7月18日。华北雨季开始时间具有显著的年际变化，但雨季发生早晚的长期变化趋势不太明显。华北雨季开始早晚与西太平洋副热带高压（简称副高）、东亚副热带西风急流、东亚夏季风等环流系统的活动关系密切，当对流层高层副热带西风急流建立偏早偏强，中层西太平洋副高第二次北跳偏早，低层东亚夏季风北进提前时，华北雨季开始偏早，反之华北雨季开始偏晚。华北雨季开始早晚与春、夏季热带印度洋、赤道中东太平洋海表温度关系显著且稳定，当Ni?o3.4指数和热带印度洋全区海表温度一致模态（IOBW）为正值时，贝加尔湖大陆高压偏强，副高偏强偏南，东亚夏季风偏弱，导致华北雨季开始偏晚；当海表温度指数为负值时，则华北雨季开始偏早。
关键词:华北雨季开始/
大气环流/
赤道东太平洋/
印度洋海表温度
Abstract:Using atmospheric data of NCEP/NCAR re-analysis, NOAA Sea Surface Temperature (SST) data, and monitoring data of the rainy season in North China from 1961-2016, the climatic characteristics of the onset date of rainy season in North China (OSDRS_NC) is analyzed. Through synthetic analysis and regression analysis, the relationship between OSDRS_NC and the atmospheric circulation system as well as SST anomalies (SSTA) is analyzed. The results show that the mean OSDRS_NC was July 18 in the past 56 years. The earliest OSDRS_NC was July 6, and the latest was August 10. The OSDRS_NC shows significant inter-annual variation, and its long-term variation trend is not obvious. The OSDRS_NC is closely linked to the activities of the western Pacific subtropical high (WPSH), the East Asian westerly jet stream (EAWJS) and the East Asian summer monsoon (EASM). When the establishment of the EAWJS, the second northward jump of the WPSH, and the northward movement of the EASM are earlier than normal, the OSDRS_NC is earlier than normal, and vice versa. The relationship between the OSDRS_NC and the SST over the Tropical Indian Ocean and the equatorial central and eastern Pacific is significant and stable in the spring and summer. When the Ni?o3.4 index and the Indian Ocean Basin-wide Warming (IOBW) display positive (negative) anomalies, the WPSH enhances (weakens) and shifts to the south, the Lake Baikal high enhances (weakens) and the EASM weakens (enhances). These anomalies lead to late (early) onset of the rainy season in North China.
Key words:Rainy season onset in North China/
Atmospheric circulation/
Equatorial East Pacific SST/
Indian Ocean SST
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