| 江淮地区夏季极端日降水事件变化特征及其与Rossby波活动的联系 |
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| 引用本文： | 孙思远,管兆勇,金大超.江淮地区夏季极端日降水事件变化特征及其与Rossby波活动的联系[J].大气科学,2022,46(1):15-26. |
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| 作者姓名： | 孙思远 管兆勇 金大超 |
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| 作者单位： | 1.南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心，南京210044 |
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| 基金项目： | 国家重点研发计划重点专项2019YFC1510201;公益性行业(气象)科研专项GYHY201406024;江苏省PAPD项目。 |
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| 摘 要： | 利用NCEP/NCAR逐日再分析资料和中国国家级地面气象站基本气象要素日值数据集，研究了1979～2016年（38年）夏季江淮地区区域性极端日降水事件的统计特征及其与Rossby波活动的联系。结果表明:在38年夏季（6～7月）中，江淮地区区域性极端日降水量的95百分位阈值为33.95 mm d?1，且共有63次极端日降水事件发生。江淮地区极端日降水事件发生时，在对流层中低层受气旋性异常环流控制，在对流层上层受反气旋性异常环流控制，为极端日降水事件的形成和维持提供了有利的斜压性环流背景。源于孟加拉湾和中国南海地区的水汽在江淮地区有较强的汇集，为极端日降水事件的发生、发展提供了有利的水汽条件。在极端日降水事件发生期间，引起江淮地区扰动涡度拟能显著变化的主要是时间平均气流对扰动涡度的平流输送项和扰动气流中的水平散度项；在极端日降水事件发生当天，对流层上层的扰动涡度拟能迅速减弱，同时在低层快速增强。波动起源于里海和黑海附近，有明显的下游频散效应，传至江淮地区约需3～5 d时间，为江淮地区极端日降水事件的形成提供了扰动能量。这些结果加深了对极端日降水事件成因的认识，并为预报预测提供了思路。
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| 关 键 词： | 江淮地区 极端日降水 Rossby波 扰动涡度拟能 |
| 收稿时间： | 2020-11-09 |
Variation Features of Summer Regional Daily Precipitation Extreme Events in Yangtze-Huaihe Rivers Region and Their Relationships with Rossby Wave Activities |
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| SUN Siyuan,GUAN Zhaoyong,JIN Dachao.Variation Features of Summer Regional Daily Precipitation Extreme Events in Yangtze-Huaihe Rivers Region and Their Relationships with Rossby Wave Activities[J].Chinese Journal of Atmospheric Sciences,2022,46(1):15-26. |
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| Authors: | SUN Siyuan GUAN Zhaoyong JIN Dachao |
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| Affiliation: | 1.Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/International Joint Laboratory on Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing 2100442.CMA (China Meteorological Administration) Earth System Modeling and Prediction Centre (CEMC), Beijing 1000813.National Meteorological Center, Beijing 100081 |
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| Abstract: | Based on the NCEP/NCAR reanalysis and the datasets of daily basic meteorological elements from China’s national meteorological stations, this study investigates the statistical characteristics of the regional daily precipitation extreme events (RDPEs) in the Yangtze–Huaihe rivers (YHR) region in eastern China from 1979 to 2016 and their relationships with Rossby wave activities. The results show that in the summer seasons (June–July) of 1979–2016, the 95th percentile threshold of the regional extreme daily precipitation in the YHR region is 33.95 mm d?1. There have been a total of 63 RDPEs in the past 38 years. The occurrence of RDPEs in the YHR region is controlled by an anomalous cyclonic circulation in the middle and lower troposphere and an anomalous anticyclonic circulation in the upper troposphere. The water vapor from the Bay of Bengal and the South China Sea has a strong concentration in the YHR region. The baroclinic circulation and sufficient water vapor are conducive to the occurrence and development of RDPEs. The eddy enstrophy in the upper troposphere over the YHR region reaches its maximum on the day before RDPEs occur and rapidly decreases thereafter. Meanwhile, the eddy enstrophy in the middle and lower troposphere reaches its maximum when RDPEs occur. This is dominated by processes including the advection term of the time average flow to the disturbed vorticity and the horizontal divergence term of the disturbed flow. Moreover, Rossby waves originate near the Caspian and Black Seas, and clearly disperse downstream. It takes approximately 3–5 days to move to the YHR region, providing disturbance energy for the formation of RDPEs in this region. Overall, these results have deepened the understanding of the reasons for the occurrence of RDPEs in the YHR region and could provide clues for effective predictions. |
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| Keywords: | Yangtze-Huaihe rivers region Extreme daily precipitation Rossby wave Eddy enstrophy |
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