江南春雨雨日的变化及其与欧亚大陆积雪的联系OACSTPCD
The variation of spring persistent rainfall days over the southern China and its relationship with snow cover over Eurasia
利用中国气象局提供的1960-2019年江南区站点观测逐日降水数据,分析了江南春雨不同持续时长雨日的变化及其与欧亚大陆积雪的联系.结果表明,江南春雨以持续5 d及以上的长持续降水为主,但降水日数下降趋势明显,导致长持续降水减少.利用奇异值分解法(Singular Value Decomposition,SVD)发现,欧亚大陆3-5月积雪覆盖率与江南春雨雨日数有显著正相关关系.将(48°～59°N,90°～110°E)区域平均积雪覆盖率定义为积雪覆盖指数,通过指数与同期大气环流的回归分析发现,当积雪偏少时,我国中北部及西伯利亚地区500 hPa位势高度正异常,在江南区850 hPa风场和水汽通量场西南向负异常,导致江南春雨雨日数减少.合成分析进一步验证了积雪偏少会在江南区形成异常东北风抑制水汽输送至江南地区,不利于降水发生.
Based on the observed daily precipitation data over the southern China from 1960 to 2019,the Spring Persistent Rainfall(SPR)duration,variation of SPR days and its relationship with snow cover in Eurasia were investigated.Results show that the SPR was mainly long-duration rainfalll with more than 5 days.The SPR days had a significant decreasing trend,which may result in the decrease of long-duration rainfall.By using Singular Value Decomposition(SVD),it is found that there is a significant positive correlation between snow cover in Eurasia and SPR days during March to May.The regional averaged snow cover rate over(48°-59°N,90°-110°E)was defined as snow cover index.The regression analysis of the snow cover index and the atmospheric circulation show that,when there was less snow cover,the geopotential height anomaly at 500 hPa was positive,the wind and water vapor flux southwest anomalies at 850 hPa were negative over the southern China,leading to the decrease of the SPR days.By composition,it was further proved that less snow cover will cause northeast wind to suppress water vapor transportation to the southern China.
柴佳明;朱坚
河海大学水文水资源学院,南京 210098河海大学水文水资源学院,南京 210098||中国气象局水文气象重点开放实验室,南京 210098
大气科学
江南春季连阴雨雨日欧亚大陆积雪
southern ChinaSPRrainfall daysEurasian snow cover
《气象科学》 2024 (002)
246-253 / 8
国家重点研发计划资助项目(2022YFC3202801)
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