| 海温异常对东亚夏季风强度先兆信号的影响 |
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| 引用本文： | 柯宗建,华丽娟,钟霖浩,杜良敏.海温异常对东亚夏季风强度先兆信号的影响[J].应用气象学报,2015,26(5):536-544. |
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| 作者姓名： | 柯宗建 华丽娟 钟霖浩 杜良敏 |
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| 作者单位： | 1.国家气候中心 中国气象局气候研究开放实验室, 北京 100081 |
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| 基金项目： | 国家重大科学研究计划（2012CB955902）,公益性行业（气象）科研专项（GYHY201306024）,国家自然科学基金项目（41005051,41205039,41105070） |
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| 摘 要： | 利用ERA-Interim再分析资料、NOAA海温资料、CMAP格点降水资料和中国气象站降水资料，通过合成、相关和回归分析等方法研究了1979—2012年东亚夏季风强度与其先兆信号的关系，并分析了热带海温异常的可能影响。研究表明:东亚夏季风先兆指数反映了2月200 hPa纬向风距平的主要模态特征 (EOF1)，前冬热带中东太平洋海温偏低 (高)，2月亚洲地区西风急流位置偏北 (偏南)，东亚夏季风先兆指数偏强 (弱)。前期热带海温异常对东亚夏季风强度有明显影响，前冬热带中东太平洋海温偏低 (高) 有利于东亚夏季风偏强 (弱)。2月亚洲中纬度地区纬向风异常特征在春季不能持续，先兆信号与东亚夏季风强度的联系主要源自热带海洋。
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| 关 键 词： | 东亚夏季风 先兆信号指数 海温 多雨带 |
| 收稿时间： | 2015-03-13 |
| 修稿时间： | 6/2/2015 12:00:00 AM |
The Influence of Sea Surface Temperature Anomaly on the East Asian Summer Monsoon Strength and Its Precursor |
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| Ke Zongjian,Hua Lijuan,Zhong Linhao and Du Liangmin.The Influence of Sea Surface Temperature Anomaly on the East Asian Summer Monsoon Strength and Its Precursor[J].Quarterly Journal of Applied Meteorology,2015,26(5):536-544. |
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| Authors: | Ke Zongjian Hua Lijuan Zhong Linhao and Du Liangmin |
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| Affiliation: | 1.Laboratory for Climate Studies, National Climate Center, Beijing 1000812.Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing 1000493.Key Laboratory of Regional Climate-Environment for East Asia RCE-TEA, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 1000294.Wuhan Regional Climate Center, Wuhan 430074 |
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| Abstract: | The strength of the East Asian Summer Monsoon (EASM) is closely connected to the summer main rainfall belt in China. The precursor index defined by the difference of zonal wind anomaly at 200 hPa between the middle latitude in Asia and eastern Pacific in February is well indicative to the strength of EASM, which is an important predicting factors in flood season. The potential mechanism of precursor signal influencing the EASM is proposed by changing the surface characteristics in South Asia continent, but it is unclear whether the atmospheric circulation anomaly in February persists in the following seasons over middle latitude region.In addition, a further investigation is needed about the surface anomaly variation over South Asia in winter-spring seasons. ERA-Interim reanalysis data, NOAA sea surface data, gridded CMAP precipitation data and precipitation observations over China are used. By composite, correlation and regression analysis approaches, the difference of wind in middle latitude over Eurasia, sea surface temperature (SST) in tropics and thermal condition in South Asia continent in previous winter-spring seasons in various strength EASM years are analyzed. Results indicate that tropical SST is the physical connection of accordant variations between the strength of EASM and its precursor.Results show that the precursor signal of EASM captures the primary feature for the first mode of empirical orthogonal function (EOF1) of zonal wind anomaly at 200 hPa over the Asia and Pacific in February. The EOF1 mode is related to SST in the central and eastern Pacific. In the previous winter, the SST is below (above) normal in the central and eastern Pacific, which is conducive to a northward (southward) shift of westerly jet over the Asia in February. The zonal wind anomaly at 200 hPa exhibits meridional positive-negative-positive (negative-positive-negative) pattern, and the precursor index is stronger (weaker) than normal. In summer, the negative (positive) SST anomaly occurs in the vicinity of Indian Ocean and South China Sea, which results in an increasing (decreasing) difference between ocean and land and stronger (weaker) Indian Summer Monsoon. Meanwhile, the western Pacific subtropical high (WPSH) is weaker (stronger) than normal, and the EASM is stronger (weaker) than normal.The anomalous feature of zonal wind in the middle latitude of the Asia in February is hardly to persist in spring. The physical connection between EASM and its precursor mainly derives from the tropical ocean. |
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| Keywords: | EASM precursor index SST rainfall belt |
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