| 夏季风期间长江流域的水汽输送状态及其年际变化 |
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| 引用本文： | 赵瑞霞,吴国雄,张宏.夏季风期间长江流域的水汽输送状态及其年际变化[J].地球物理学报,2008,51(6):1670-1681. |
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| 作者姓名： | 赵瑞霞 吴国雄 张宏 |
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| 作者单位： | 1.中国气象局国家气象中心，北京 100081;2.中国科学院大气物理研究所LASG实验室，北京 100029;3.中国气象局气象探测中心，北京 100081 |
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| 基金项目： | 国家气象局气候变化专项课题
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科技部资助项目
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国家自然科学基金
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| 摘 要： | 本文利用NCEP/NCAR再分析资料,分析了长江流域夏季风期间的水汽收支和循环，着重研究了不同月份与水汽收支的年际变化显著相关的大尺度水汽输送和环流异常.流域范围的西南夏季风水汽输送以6、7月最为强烈，经向输送在5～8月造成流域水汽辐合，9月造成辐散；纬向输送在5～7月造成流域水汽辐散，8、9月造成辐合.研究表明，在不同月份，流域的南北边界处的水汽输送在流域水汽收支的年际变化中起着不同的作用.这种变化与大气环流的异常密切相关.在夏季风相对较弱月份（5、8、9月），流域水汽收支的年际变化极大地受到流域南边界南风水汽输入通道的影响，对应于水汽收入偏丰年，该3个月500 hPa高空在青藏高原东部都存在显著异常低压区，而且，8、9月在中南半岛及其以东洋面存在显著异常反气旋环流，与8月西太副高的向西向南异常伸展，以及9月副高的西伸较弱和南北范围较宽有关，这些异常环流均造成南边界的大量异常水汽输入.而在夏季风十分强盛的6、7月，流域北边界南风水汽输出极大增加，成为流域水汽收入年际变化的关键敏感通道，对应于水汽收入偏丰年，6月500 hPa高空主要受中纬度以黄海和东海为中心的异常低压系统和气旋性异常环流影响，与该区域副高偏南、偏弱有关，而7月则主要受中高纬以外兴安岭为中心的异常高压和反气旋性异常环流影响，应该是由于该区域大陆高压的频繁生成造成的，它们均造成流域北边界水汽输出的异常减少.
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| 关 键 词： | 长江流域 水汽循环 夏季风 年际变化 异常环流 |
| 收稿时间： | 2007-1-29 |
| 修稿时间： | 2008-9-11 |
Seasonal characteristic and interannual variability of the atmospheric hydrological cycle in the Yangtze River basin during the summer monsoon period |
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| ZHAO Rui-Xia,WU Guo-Xiong,ZHANG Hong.Seasonal characteristic and interannual variability of the atmospheric hydrological cycle in the Yangtze River basin during the summer monsoon period[J].Chinese Journal of Geophysics,2008,51(6):1670-1681. |
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| Authors: | ZHAO Rui-Xia WU Guo-Xiong ZHANG Hong |
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| Institution: | 1.National Meteorological Center, China Meteorological Administration, Beijing 100081, China;2.LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;3.Meteorological Observation Centre, China Meteorological Administration, Beijing 100081, China |
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| Abstract: | The atmospheric hydrological cycle over the Yangtze River basin during summer monsoon period is examined using the NCEP/NCAR reanalysis.The primary focus is the linkage between the interannual variability of the moisture convergence in Yangtze River and the large-scale water vapor transport and circulation fields.The southwest wind over the basin is strongest during June to July.The meridional water vapor transport makes convergence over the river in May to August,and divergence over it in September;and the zonal water vapor transport makes divergence over the river in May to July,and convergence over it in August to September.During the period when the summer monsoon is comparatively weaker over the east of China,such as May,August and September,the interannual variation of the water vapor budget over the river is significantly affected by the variation of the south wind across the south boundary.While the Yangtze River is unusually wet,an anomalous low-pressure is established over the east of Qinghai-Tibet plateau for the three months,and an anomalous anti-cyclonic circulation accompanied with a positive air pressure anomaly is established over Indo-China Peninsula as well as its eastern ocean in August and September.These two anomalous circulations all increase the water vapor input through the south boundary.But during the period when the summer monsoon is comparatively stronger over the east of China,such as June and July,the water vapor output by the south wind across the north boundary is evidently increased,and becomes the most vital path for the interannual variation of the water vapor budget over the river.While the river is unusually wet,an anomalous cyclonic circulation accompanied with a negative pressure anomaly is established in June over the Yellow Sea and the East China Sea in mid-latitude,and an anomalous anti-cyclonic circulation accompanied with a positive air pressure anomaly is established in July over the region around the outer Xinganling mountain in mid and high latitude.These two different anomalous circulations all decrease the water vapor output through the north boundary. |
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| Keywords: | Yangtze River basin Water vapor cycle Summer monsoon Interannual variability Anomalous circulation |
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