大气科学  2018, Vol. 42 Issue (5): 1081-1095   PDF    
不同类型和强度的厄尔尼诺事件对次年华南前汛期降水的可能影响
伍红雨1,2, 吴遥3     
1 广东省气候中心, 广州 510641
2 中国气象局广东省区域数值天气预报重点实验室, 广州 510641
3 重庆市气候中心, 重庆 401147
摘要: 根据气象行业标准(QT/T370-2017)对厄尔尼诺事件不同类型的划分结果以及国家气候中心最新颁布的华南前汛期业务监测标准,利用1961~2016年NCEP/NCAR日、月尺度再分析大气环流资料、海表温度资料(ERSST V4)以及华南261个国家气象观测站逐日降水资料,采用相关、合成等方法分析了不同类型、强度的厄尔尼诺事件特征以及与次年华南前汛期的关系,并探讨其海温和大气环流异常特征。结果表明,厄尔尼诺事件的类型、强度对次年华南前汛期降水的影响存在明显差异。中等及以上强度东部型厄尔尼诺事件次年,华南前汛期开汛早、结束晚,前汛期持续时间长、降水多;弱等级的东部型以及中部型厄尔尼诺事件次年则相反。在厄尔尼诺事件次年华南前汛期,中等及以上强度东部型厄尔尼诺相对弱东部型或中部型厄尔尼诺的大气环流存在明显差异。高层西风急流明显加强,中层北半球极涡加强,东亚大槽强,低层菲律宾以东存在反气旋异常环流,华南存在南北风的交汇和水汽辐合加强,有利于华南前汛期降水偏多。
关键词: 厄尔尼诺事件      类型      强度      前汛期降水      华南     
Possible Impacts of El Niño Events of Different Types and Intensity on Precipitation in the Subsequent First Rainy Season in South China
WU Hongyu1,2, WU Yao3     
1 Climate Center of Guangdong Province, Guangzhou 510641
2 Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, China Meteorological Administration, Guangzhou 510641
3 Chongqing Climate Center, Chongqing 401147
Abstract: Based on the meteorological industry standard(QT/T370-2017)for El Niño events of different types and the latest monitoring standard of the first rainy season in South China issued by National Climate Center, using the NCEP/NCAR daily and monthly reanalysis data, NOAA SST data (ERSST V4), and the data collected at 261 meteorological observational stations in South China from 1961 to 2016, the relationship between El Niño events of different types and intensity and precipitation in the subsequent first rainy season in South China and the characteristics of the atmospheric circulation and SST are analyzed by correlation and composite analysis methods. The results show that the impacts of El Niño events of different types and intensity on the subsequent first rainy season in South China are obviously different. Under the influence of the East Pacific El Niño events with medium and higher intensity, the onset date of the first rainy season in South China is earlier than normal while the ending date is later than normal and the duration is longer with higher than normal precipitation. The opposite is true when South China is under the influence of East Pacific El Niño events with weak intensity or under the influence of central Pacific El Niño events. The atmospheric circulation in the first rainy season in South China under the influence of East Pacific El Niño events with medium and higher intensity is obvious different from that under the influence of weak East Pacific El Niño events or central Pacific El Niño events. In the former condition, the westerly jet in upper levels intensify, the polar vortex in the Northern Hemisphere and the East Asia major deep trough both become stronger than normal, an anomalous anticyclone develops to the east of the Philippines in the middle levels, and moisture convergence occurs in South China where southerly and northerly winds converge.
Keywords: El Niño events      Types      Intensity      Precipitation in the first rainy season      South China     
1 引言

关于ENSO事件分布型的研究是近几年非常热门的话题,主要原因可能是2000年以来发生的厄尔尼诺事件基本都不同于传统的厄尔尼诺事件,最大海温正距平分布的区域不在传统定义ENSO事件的Niño3区,而是向西移动到日界线附近,由此带来的气候影响也与传统ENSO事件的影响有着明显的差异( 任福民等,2012袁媛等,2012a),因此,这一现象引起了气象学家广泛的关注。2005年以来,科学家们研究发现ENSO事件发展过程中,赤道中东太平洋海表温度异常的空间分布形态不仅对热带对流加热场分布特征的影响存在显著差异,其发生机理及气候影响也不同(Larkin and Harrison, 2005Ashok et al., 2007Weng et al., 2007Kug et al., 2009Kao and Yu, 2009袁媛等, 2012a, 2014徐霈强等,2016)。Yeh et al.(2009)提出中部型El Niño事件在1990年代后发生的频率显著增加可能与全球气候变暖,尤其是赤道太平洋海温的年代际增暖有关。中部型厄尔尼诺与东部型厄尔尼诺对南美、北美西海岸以及日本等气候的可能影响几乎相反(Larkin and Harrison, 2005Ashok et al., 2007)。中部型厄尔尼诺会导致美国西部冬季常出现北干南湿,而东部型厄尔尼诺发生时美国西部冬季以偏湿的气候特征为主(Weng et al., 2007)。袁媛等(2012a)参考Kug et al.(2009)对厄尔尼诺事件的研究,根据厄尔尼诺事件发展达到盛期时海温距平分布特点,将1950年以来的厄尔尼诺事件分为