江南春雨的时空分布特征及其旱涝年环流差异
投稿时间:2015-08-12  修订日期:2016-01-28  点此下载全文
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王黎娟 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, 江苏 南京 210044 wljfw@163.com 
高龙龙 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, 江苏 南京 210044
射阳县气象局, 江苏 盐城 224300 
 
基金项目:江苏省高校自然科学研究重大项目(14KJA170004);公益性行业(气象)科研专项(GYHY201406001);江苏省自然科学基金项目(BK20131432);江苏省“青蓝工程”;江苏省“333”工程
中文摘要:利用1979—2010年中国753站逐日降水资料,定义了江南春雨时间范围(12—27候)和空间范围(110~120°E,23~30°N),并通过EOF方法分析了江南春雨的时空分布特征,得到3个主要模态:全区一致型、南北反相型和东西反相型。在此基础上,利用NCEP/NCAR再分析资料合成分析了江南春雨的旱涝年的环流差异。结果表明:江南春雨偏涝年,上游青藏高原东南侧的西南风增强,西太平洋副热带高压加强西伸,有利于来自副高南侧的水汽与高原南侧的水汽汇合向江南地区输送,而江南地区的上升运动也明显加强,有利于江南地区降水的产生。进一步分析发现在春雨期涝年青藏高原的热源强度明显强于旱年,导致高原东南侧的绕流增强,进而有利于江南地区的降水,而旱年情况大致相反。此外,比较旱涝年西太平洋—东亚大陆之间的纬向海陆热力差异发现,涝年大约在第11候发生冷热源的反转,旱年则在第16候反转。涝年江南地区春雨期热源强度也明显强于旱年,进一步说明江南地区冷热源的反转以及增强对于江南地区的降水具有重要的作用,同时对于判定江南春雨的季风降水性质具有重要指示意义。
中文关键词:江南春雨  时空分布  环流差异  纬向海陆热力差异
 
The spatial and temporal distribution of the spring persistent rains and circulation differences between its drought and flood years
Abstract:Based on the daily precipitation data from 753 stations in China during 1979 and 2010, the spatial scale(23—30°N, 110—120°E) and time range(from pentad 12 to 27) of the Spring Persistent Rains(SPR) are redefined, and the spatial and temporal distribution of SPR are analyzed by EOF(empirical orthogonal function) method.Three main modes, namely, the region consistent type, south-north reverse type and east-west reverse type, are obtained.On this basis, by using the NCEP/NCAR reanalysis dataset, we analyzed the circulation differences between SPR drought and flood years.The results show that in drought years, the southwester over the southeast area of Tibet Plateau strengthens and the western Pacific subtropical high enhances and extends westward, which are conducive to water vapor transport from the south of the plateau and of the subtropical high to the south area of the Yangtze River, and further induce the enhancement of ascending motion and precipitation over the south area of the Yangtze River.Further analysis shows that the heat source intensity over Tibet Plateau in SPR flood years is obviously stronger than that in SPR drought years, which leads to the enhancement of the flow around the southwestern side of the plateau.Therefore, it is conducive to the precipitation in the south area of the Yangtze River.But in drought years, the situation is just the opposite.In addition, by comparing the zonal land-sea thermal differences between East Asia continent and the Western Pacific, it is found that the inversion between cold and heat source occurs at about the 11th pentad in flood years.However, the atmospheric source reverses at the 16th pentad in drought years.The intensity of heat source during SPR over the south area of the Yangtze River in flood years is also stronger than that in drought years, which further explains that the inversion and enhancement of the zonal land-sea thermal contrast play an important role in producing the SPR, and it is also an important indicator in determining the monsoon precipitation characteristics of the SPR.
keywords:SPR  spatial and temporal distribution  circulation differences  the zonal land-sea thermal contrast
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