南亚和东亚热带夏季风强弱不同配置及其对中国夏季降水的影响

利用NOAA向外长波辐射(OLR)、NCEP/NCAR再分析资料和CN05.1降水资料,研究了南亚和东亚热带夏季风强度年际变化关系,及其强弱不同配置对中国夏季降水的影响。结果表明:南亚和东亚热带夏季风强度变化之间存在同相和反相两种配置,定义的强度同相和反相变化指数可以很好地表征该关系。同相变化模态可能与海温异常时的强El Nino(La Nina)影响有关,其反相变化模态受El Nino(La Nina)以及印度洋海盆一致模的影响,同时西太平洋副热带高压和伊朗高压位置东西偏移和强度变化也影响着不同配置的出现。两者不同配置时,对中国夏季降水的影响不同。当变化呈同相偏强时,夏季中国东部地区降水为“中间少南北多”的雨型。当变化呈反相,东亚热带夏季风偏强南亚夏季风偏弱时,夏季中国东部地区降水为“一致偏少”雨型。

Different configurations of interannual variation between East Asian tropical summer monsoon and South Asian summer monsoon and the impact on China summer rainfall

By using the monthly averages of Outgoing Longwave Radiation (OLR) data from National Oceanic and Atmospheric Administration (NOAA), NCEP-NCAR reanalysis dataset, and CN05.1 daily precipitation dataset, the relationship of interannual variation between East Asian Tropical Summer Monsoon (EATSM)and South Asian Summer Monsoon(SASM) was analyzed, and the impact of different strength change configurations on China summer rainfall was investigated. Results show that: there are two configurations with in-phase and out-of-phase variations between the intensity of EATSM and SASM. The identical and inverse intensity change indices are defined, and they can represent the relationship well. The in-phase mode may be related to the influence of the strong El Niño (La Niña), and the antiphase mode may be influenced by El Niño (La Niña) and Indian Ocean Basin-wide. At the same time, the east-west deviation and intensity variation of the WPSH and the Iran High also affect the appearance of different configurations. When the intensity of EATSM and SASM changes in different configurations, the effects on China summer rainfall are different. When EATSM and SASM are stronger, the rainy model of summer rainfall in the eastern part shows "less in the middle, more in the south and north". When the intensity of EATSM and SASM changes in out-of-phase, with stronger East Asia tropical summer monsoon and weaker South Asia summer monsoon, the precipitation in eastern China shows in consistently less rainy pattern.