| 北方雨季中国东部降水异常模态的环流特征及成因分析 |
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| 引用本文： | 郭恒,张庆云.北方雨季中国东部降水异常模态的环流特征及成因分析[J].大气科学,2016,40(5):946-964. |
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| 作者姓名： | 郭恒 张庆云 |
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| 作者单位： | 1.中国科学院大气物理研究所国际气候与环境科学中心, 北京 100029;中国科学院大学, 北京 100049 |
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| 基金项目： | 国家自然科学基金项目41375055，国家重点基础研究发展计划2014CB954301、2012CB957803 |
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| 摘 要： | 根据1958～2011年中国东部（105°E以东）316站逐日降水资料及NCEP/NCAR逐日再分析资料，利用统计分析、物理量诊断等方法，探讨北方雨季（7月11日至8月31日）中国东部降水异常模态及同期、前期的大气环流特征。分析发现，北方雨季中国东部降水异常表现为三个相互独立的降水模态:第一模态为偏西型，当其时间系数为正（负）时，河套地区降水偏多（少），江淮流域上游降水偏少（多），南方大部降水偏多（少）；第二模态为北方一致型，当其时间系数为正（负）时，北方降水一致偏多（少），长江流域降水偏少（多）；第三模态为偏东型，当其时间系数为正（负）时，东北南部至长江中游降水偏多（少），华东沿海降水偏少（多）。研究发现，造成北方雨季三个降水异常模态的环流特征各不相同:偏西型降水主要受西亚高空副热带西风急流位置南北偏移影响；北方一致型降水主要由东亚-太平洋遥相关波列导致；偏东型降水主要与海陆气压异常对比造成的东亚夏季风变化有关。此外，三个模态与前期环流异常有密切联系。第一模态的正（负）异常由7月上旬200 hPa来自北大西洋的异常波列造成乌拉尔山位势高度负（正）异常和巴尔喀什湖以南位势高度正（负）异常引起。第二模态的正（负）异常与前期7月上旬200 hPa北大西洋上位势高度负（正）异常产生的沿中纬度（高纬度）路径向下游传播的波列有关。第三模态的正（负）异常由春季3月份低层蒙古上空异常的气旋（反气旋）持续至同期造成。
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| 关 键 词： | 北方雨季 降水异常 西风急流 副热带高压 |
| 收稿时间： | 2015/6/24 0:00:00 |
The Dominant Modes of Precipitation Anomalies over Eastern China during the Northern China Rainy Season and the Possible Causes |
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| GUO Heng and ZHANG Qingyun.The Dominant Modes of Precipitation Anomalies over Eastern China during the Northern China Rainy Season and the Possible Causes[J].Chinese Journal of Atmospheric Sciences,2016,40(5):946-964. |
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| Authors: | GUO Heng and ZHANG Qingyun |
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| Institution: | 1.International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;University of Chinese Academy of Sciences, Beijing 1000492.International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | Based on the daily mean rainfall data at 316 China meteorological stations and the NCEP-NCAR reanalysis dataset for 1958-2011, the dominant modes of precipitation anomalies over eastern China (east of 105°E) during the northern China rainy season (11 July to 31 August) and the accompanying circulation as well as precursors, are investigated with EOF and composite analysis, along with other methods. The results show that there are three dominant modes-the first EOF mode (EOF1) depicting a meridional tripole pattern, the second EOF mode (EOF2) depicting a seesaw precipitation anomaly between northern China and the Yangtze River valley, and the third EOF mode (EOF3) depicting a seesaw precipitation anomaly between areas from Northeast China to the upper reaches of the Yangtze River and coastal areas in East China. The major circulation characteristics resulting in the three modes are different. EOF1 is attributed to the meridional displacement of the West Asian subtropical westerly jet stream (WAJS), EOF2 is attributed to the East Asian-Pacific (EAP) teleconnection pattern, and EOF3 is attributed to the anomalous East Asian summer monsoon (EASM) due to an anomalous sea level pressure gradient between East Asia and the western North Pacific. Possible causes of the above anomalous circulation are also analyzed. For EOF1, the 200 hPa wave train from the North Atlantic causes the seesaw geopotential height anomalies between the Ural mountains and Balkhash Lake in early July, leading to the meridional displacement of the WAJS. For EOF2, the EAP teleconnection pattern is closely associated with the geopotential height anomaly over the North Atlantic and corresponding wave train dating from early July. For EOF3, the anomalous cyclonic/anticyclonic circulation over Mongolia beginning from March is the precursor of stronger/weaker EASM. |
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| Keywords: | Northern China Rainy Season Anomalous precipitation Westerly jet stream Western Pacific subtropical high |
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