| 冬季和春季印度洋海温异常年际变率模态对中国东部夏季降水的可能影响过程 |
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| 引用本文： | 徐志清,范可.冬季和春季印度洋海温异常年际变率模态对中国东部夏季降水的可能影响过程[J].大气科学,2012,36(5):879-888. |
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| 作者姓名： | 徐志清 范可 |
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| 作者单位： | 1.中国科学院大气物理研究所竺可桢—南森国际研究中心,北京 100029;中国科学院研究生院,北京 100049 |
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| 基金项目： | 全球变化研究国家重大科学研究计划2010CB950304,公益性行业 (气象) 科研专项GYHY200906018,中国科学院知识创新工程重要方向项目KZCX2-YW-BR-14,国家自然科学基金资助项目41175071 |
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| 摘 要： | 印度洋热力状况是影响全球气候变化和亚洲季风变异的一个重要的因素,但以往研究更多关注热带印度洋海温的变化,对南印度洋中高纬地区海温变化关注不够,由此限制了我们对印度洋的全面认识.本文研究了年际尺度上整个印度洋海温异常主导模态的特征及其对我国东部地区夏季降水的可能影响过程,以期望为气候变异研究及预测提供理论依据.研究结果表明:全印度洋海温异常年际变率的主导模态特征是在南印度洋副热带地区海温异常呈现西南—东北反向变化的偶极子模态,西极子位于马达加斯加以东南洋面,东极子位于澳大利亚以西洋面;同时,热带印度洋海温异常与东极子一致.当西极子为正的海温异常,东极子、热带印度洋为负异常时定义为正的印度洋海温异常年际变率模态;反之,则为负的印度洋海温异常年际变率模态.从冬至春,印度洋海温异常年际变率模态具有较好的季节持续性;与我国长江中游地区夏季降水显著负相关,而与我国华南地区夏季降水显著正相关.其可能的影响过程为:对于正的冬、春季印度洋海温异常年际变率模态事件,印度洋地区异常纬向风的经向大气遥相关使得热带印度洋盛行西风异常,导致春、夏季海洋性大陆对流减弱,使夏季西太平洋副热带高压强度偏弱、位置偏东偏北,造成华南地区夏季降水增多,长江中游地区降水减少;反之亦然.同时,印度洋海温异常年际变率模态可通过改变印度洋和孟加拉湾向长江中游地区的水汽输送而影响其夏季降水.
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| 关 键 词： | 印度洋 海温异常年际变率模态 中国东部夏季降水 经向大气遥相关 |
| 收稿时间： | 2011/9/27 0:00:00 |
| 修稿时间： | 4/1/2012 12:00:00 AM |
Possible Process for Influences of Winter and Spring Indian Ocean SST Anomalies Interannual Variability Mode on Summer Rainfall over Eastern China |
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| XU Zhiqing and FAN Ke.Possible Process for Influences of Winter and Spring Indian Ocean SST Anomalies Interannual Variability Mode on Summer Rainfall over Eastern China[J].Chinese Journal of Atmospheric Sciences,2012,36(5):879-888. |
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| Authors: | XU Zhiqing and FAN Ke |
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| Institution: | 1.Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Graduate University of Chinese Academy of Sciences, Beijing 1000492.Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Key Laboratory of Regional Climate-Environment for East Asia, Chinese Academy of Sciences Beijing 100029 |
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| Abstract: | The thermal conditions of the Indian Ocean is an important factor that can affect the global climate and Asian monsoon variability. Previous studies have paid much more attention to sea surface temperature (SST) variability in the tropical Indian Ocean than the middle-and high-latitude South Indian Ocean, which limits the overall understanding about the Indian Ocean. This study presents the leading mode of the Indian Ocean sea surface temperature anomalies (SSTA) on interannual time scale and the possible process for its influences on summer rainfall over eastern China, ex- pecting to provide a theoretic basis for climate variations research and prediction. The results indicate that the leading mode of the Indian Ocean SSTA on interannual time scale is characterized by southwest-northeast oriented dipole oscil- lation in the subtropical South Indian Ocean. The western pole is located in the southeast of Madagascar and the eastern pole lies in the west of Australia, varying consistently with the tropical Indian Ocean SSTA. Here, the positive (negative) Indian Ocean SSTA interannual variability mode is defined as positive (negative) SSTA in the western pole and negative (positive) SSTA in the eastern pole and the tropical Indian Ocean. The interannual variability mode, which can persist during winter and spring, is significantly negatively correlated with summer rainfall over the middle reach of the Yangtze River (MYR), but significantly positively correlated with rainfall over South China (SC). The possible mechanism can be described as follows: for positive Indian Ocean SSTA interannual variability mode events during winter and spring, the meridional atmospheric teleconnection of zonal wind anomalies in the Indian Ocean leads to westerly anomalies in the tropical Indian Ocean which depress the convective activities over the Maritime Continent in spring and summer. The depressed convective activities make the western Pacific subtropical high weaken and shift northward and eastward, conducing to increased rainfall over SC and reduced rainfall over MYR, and vice versa. Moreover, the Indian Ocean SSTA interannual variability mode can also influence summer rainfall over MYR by changing its water vapor transport stemming from the Indian Ocean and the Bay of Bengal. |
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| Keywords: | Indian Ocean SSTA interannual variability mode summer rainfall over eastern China meridional atmospheric teleconnection |
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