热带大气季节内振荡对华南后汛期降水的影响

Impact of the Madden-Julian Oscillation on Post-flood Season Precipitation in South China

为研究MJO对中国华南后汛期(7-9月)降水的影响。采用合成分析方法,使用一套中国区域高分辨率降水格点数据(CN05.1)与实时热带大气季节内振荡(MJO)指数。结果表明,随着MJO对流活动中心从热带印度洋进入太平洋,华南后汛期降水呈现明显差异。当MJO对流活动传至东印度洋并有部分向北延伸时(第3位相)或进入西太平洋(第7、8位相)时,华南后汛期出现较大的降水正异常;当对流活动中心处于西印度洋(第2位相)或处于南海及西太平洋(第4、5位相)时,出现降水负异常。进一步研究显示,MJO主要是通过引起大尺度环流、水汽输送异常进而影响华南后汛期降水。

In this paper, to investigate the impact of the Madden-Julian Oscillation （MJO） on the post-flood season precipitation （July to September） in South China the gridded daily precipitation data with high resolution over China （ CN05.1 ） and the Real-time Multivariate MJO （RMM） index. The composite analyses reveals fundamental differences of the post-flood season precipitation during MJO convection eastward phase, initiation over the tropic Indian Ocean and eastward propagation into the Pacific Ocean. The positive precipitation anomalies were starkest while MJO convection activity is centered over the eastern Indian Ocean with northward propagation in part preferentially （ phase3 ） or reaches the western Pacific Ocean （ phase7, phase8）. The negative precipitation anomalies associate with the MJO convection mostly manifested over the western Indian Ocean （ phase2 ）, the South China Sea （ phase 4 ）, as well as the Western Pacific （phaseS）. Further research shows that post-flood season precipitation is affected through variations of large-scale atmospheric circulation together with the moisture transportation, which is induced by MJO convection.