| The Impact of Mid- and High-Latitude Rossby Wave Activities on the Medium-Range Evolution of the EAP Pattern During the Pre-Rainy Period of South China |
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| 作者姓名： | 施宁 布和朝鲁 纪立人 王盘兴 |
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| 作者单位： | SHI Ning,WANG Panxing(College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044);BUEH Cholaw,JI Liren(Center for Disastrous Climate Research and Prediction, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics,Chinese Academy of Sciences, Beijing 100029) |
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| 基金项目： | 国家重点基础研究发展规划(973计划)，国家自然科学基金 |
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| 摘 要： | Based on the NCEP DOE AMIP II daily reanalysis data (1979–2005), the evolution of the East Asia/Pacific (EAP) teleconnection pattern during the pre-rainy period of South China is studied on the medium-range time scale. It is found that positive and negative EAP patterns share a similar generation process. In the middle and upper troposphere, Rossby wave packets emanating from the northeast Atlantic or Europe prop-agate toward East Asia along the Eurasian continent waveguide and finally give rise to the three anomaly centers of the EAP pattern over East Asia. Among the three anomaly centers, the western Pacific subtropical center appears the latest. Rossby wave packets propagate from the high latitude anomaly center toward the mid-latitude and the subtropical ones. The enhancement and maintenance of the subtropical anomaly center is closely associated with the subtropical jet waveguide and the incoming Rossby wave packets from the upstream. In the lower troposphere, Rossby wave packets emanate from the subtropical Asia toward East Asia. Positive and negative EAP patterns could not be regarded as "mirrors" to each other with simply reversed phase. For the positive pattern, the positive height anomaly center around the Scandinavia Peninsula keeps its strength and position during the mature period, and the Rossby wave packets thus propagate persistently toward East Asia, facilitating a longer mature time of the positive pattern. As for the formation of the negative EAP pattern, however, the incoming Rossby wave energy from the upstream contributes to both the enhancement and southeastward movement of the negative anomaly belt from the Yenisei River to the Bering Strait and the positive anomaly center around Mongolia. At the peak time, the two anomlous circulations are evolved into the Northeast Asia and the mid-latitude anomaly centers of the negative pat- tern, respectively. The energy dispersion of Rossby wave packets is relatively fast due to the predominant zonal circulation in the extratropics, causing a shorter mature period of the negative pattern. During the pre-rainy period of South China, the prevalence of the EAP pattern significantly affects the rainfall over the region south of the Yangtze River. The positive (negative) EAP pattern tends to cause positive (negative) precipitation anomalies in that region. This is different from the earlier research findings based on monthly mean data.
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| 关 键 词： | 罗斯比波 高空天气图 介质范围 东亚地区 |
The Impact of Mid- and High-Latitude Rossby Wave Activities on the Medium-Range Evolution of the EAP Pattern During the Pre-Rainy Period of South China |
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| SHI Ning,BUEH Cholaw,JI Liren,WANG Panxing.The Impact of Mid- and High-Latitude Rossby Wave Activities on the Medium-Range Evolution of the EAP Pattern During the Pre-Rainy Period of South China[J].Acta Meteorologica Sinica,2009,23(3):300-314. |
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| Authors: | SHI Ning BUEH Cholaw JI Liren WANG Panxing |
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| Affiliation: | [1]College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044 [2]Center for Disastrous Climate Research and Prediction, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 [3]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | Based on the NCEP DOE AMIP II daily reanalysis data (1979-2005), the evolution of the East Asia/Pacific (EAP) teleconnection pattern during the pre-rainy period of South China is studied on the medium-range time scale. It is found that positive and negative EAP patterns share a similar generation process. In the middle and upper troposphere, Rossby wave packets emanating from the northeast Atlantic or Europe propagate toward East Asia along the Eurasian continent waveguide and finally give rise to the three anomaly centers of the EAP pattern over East Asia. Among the three anomaly centers, the western Pacific subtropical center appears the latest. Rossby wave packets propagate from the high latitude anomaly center toward the mid-latitude and the subtropical ones. The enhancement and maintenance of the subtropical anomaly center is closely associated with the subtropical jet waveguide and the incoming Rossby wave packets from the upstream. In the lower troposphere, Rossby wave packets emanate from the subtropical Asia toward East Asia.Positive and negative EAP patterns could not be regarded as "mirrors" to each other with simply reversed phase. For the positive pattern, the positive height anomaly center around the Scandinavia Peninsula keeps its strength and position during the mature period, and the Rossby wave packets thus propagate persistently toward East Asia, facilitating a longer mature time of the positive pattern. As for the formation of the negative EAP pattern, however, the incoming Rossby wave energy from the upstream contributes to both the enhancement and southeastward movement of the negative anomaly belt from the Yenisei River to the Bering Strait and the positive anomaly center around Mongolia. At the peak time, the two anomlous circulations are evolved into the Northeast Asia and the mid-latitude anomaly centers of the negative pattern, respectively. The energy dispersion of Rossby wave packets is relatively fast due to the predominant zonal circulation in the extratropics, causing a shorter mature period of the negative pattern.During the pre-rainy period of South China, the prevalence of the EAP pattern significantly affects the rainfall over the region south of the Yangtze River. The positive (negative) EAP pattern tends to cause positive (negative) precipitation anomalies in that region. This is different from the earlier research findings based on monthly mean data. |
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| Keywords: | Rossby wave medium range process EAP (East Asia/Pacific) pattern pre-rainy period of South China precipitation |
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