| 春季南半球环状模与长江流域夏季降水的关系：Ⅰ 基本事实 |
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| 引用本文： | 南素兰,李建平.春季南半球环状模与长江流域夏季降水的关系：Ⅰ 基本事实[J].气象学报,2005,63(6):837-846. |
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| 作者姓名： | 南素兰 李建平 |
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| 作者单位： | 1. 兰州大学大气科学学院,兰州,730000;中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京,100029
2. 中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京,100029 |
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| 基金项目： | 国家自然科学基金项目(40221503,40275025)，CAS项目(ZKCX2-SW-210) |
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| 摘 要： | 利用统计方法对春季(4~5月)南半球环状模(SAM)与夏季(6~8月)中国降水的关系作了分析,发现春季南半球环状模指数(SAMI)与夏季长江中下游降水之间存在显著的正相关关系。春季SAM偏强的同期对流层下层在欧亚大陆存在一以蒙古高原和天山山脉为中心的异常反气旋对,从中国东北到华南中纬度地区均为异常的偏北气流控制。这种环流异常形式可以持续到夏季并加强,致使东亚夏季风减弱;春季SAM偏强,夏季西太平洋副热带高压西部脊强度加强,位置偏西,这些异常环流都有利于长江中下游地区降水偏多。另外,春季SAM偏强,夏季长江中下游地区水汽含量增大,向上的垂直运动得到加强,为该地区降水偏多提供了基本的水汽条件。春季SAM偏弱时,夏季东亚大气环流和水汽条件相反。因此,春季SAM为夏季长江中下游汛期降水提供了一有用的前期信号。
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| 关 键 词： | 南半球环状模 长江流域降水 正相关 东亚大气环流 |
| 收稿时间： | 2005/4/13 0:00:00 |
| 修稿时间： | 2005年4月13日 |
THE RELATIONSHIP BETWEEN THE SUMMER PRECIPITATION IN THE YANGTZE RIVER VALLEY AND THE BOREAL SPRING SOUTHERN HEMISPHERE ANNULAR MODE:Ⅰ BASIC FACTS |
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| Nan Sulan and Li Jianping.THE RELATIONSHIP BETWEEN THE SUMMER PRECIPITATION IN THE YANGTZE RIVER VALLEY AND THE BOREAL SPRING SOUTHERN HEMISPHERE ANNULAR MODE:Ⅰ BASIC FACTS[J].Acta Meteorologica Sinica,2005,63(6):837-846. |
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| Authors: | Nan Sulan and Li Jianping |
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| Abstract: | The relationship between the boreal spring(April-May) southern hemisphere annular mode(SAM) and the following summer(June-August) rainfall in China was examined statistically.The results show there are a significantly positive correlation between the boreal spring SAM index(SAMI) and the following summer precipitation in the middle and lower reaches of the Yangtze River valley.In the spring,a pair of anomalous anticyclones exists in the Mongolia Plateau and Tianshan Mountains respectively while there is spring strong SAM.Meanwhile the anomalous northerlies prevail from the middle latitudes of East Asia to South China throughout northeast of China.These anomalous circulations may continue to the following summer and weaken East Asian summer monsoon(EASM).The west ridge of western Pacific subtropical high strengthens and extends westward in summer following the spring strong SAM.These circulation anomalies are related to the above normal precipitation in the middle and lower reaches of the Yangtze River valley.Moreover,the spring strong SAM is followed by increased ascending vertical velocity,specific humidity and relative humidity,which provide necessary water vapor conditions for increasing the summer precipitation in the middle and lower reaches of the Yangtze River valley,and vice versa.The boreal spring SAM variation provides a potential valuable signal for predicting the summertime precipitation in the middle and lower reaches of the Yangtze River valley. |
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| Keywords: | Southern hemisphere annular mode(SAM) Precipitation Yangtze River valley Positive correlation |
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