双月刊

ISSN 1006-9895

CN 11-1768/O4

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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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

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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


Summer Regional Daily-Precipitation Extreme Events in Yangtze-Huai Rivers Region of China and Their Relationships with Rossby Wave Activities
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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

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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,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天时间,为江淮地区极端日降水事件的形成提供了扰动能量。这些结果加深对极端日降水事件成因的认识,并为预报预测提供了思路。

    Abstract:

    Based on NCEP/NCAR reanalysis and datasets of daily basic meteorological elements from China national meteorological stations, the statistical characteristics of The regional daily-precipitation extreme events (RDPEs) in the Yangtze-Huai Rivers (YHR) region in eastern China from 1979 to 2016 and their relationships with Rossby wave activities are investigated. The results show that in the summers (June-July) of 1979-2016, the 95th percentile threshold of regional extreme daily-precipitation in YHR region is 33.95 mm/d. There are 63 RDPEs in total in the past 38 years. When RDPEs occur in YHR region, it 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 YHR region. Baroclinic circulation and sufficient water vapor are conducive to the occurrence and development of RDPEs. The eddy enstrophy in the upper troposphere over YHR region reaches its maximum on the day before RDPEs occur and rapidly decreases from then on. 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 Sea and the Black Sea and obviously disperse downstream-ward. It takes about 3-5 days to move to YHR region, providing disturbance energy for the formation of RDPEs in this region. Overall, these results have deepened the understanding of the reasons for RDPEs in YHR region and could provide clues for effective predictions.

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  • 收稿日期:2020-11-09
  • 最后修改日期:2021-08-07
  • 录用日期:2021-08-26
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