1991和1994年南京夏季降水异常与副热带东北太平洋海温异常的联系及成因
投稿时间:2018-03-29  修订日期:2018-06-05  点此下载全文
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胡杨 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
金大超 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044 jindc@nuist.edu.cn 
米热阿衣·台来提 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
基金项目:江苏省自然科学基金资助项目(BK20160956);南京信息工程大学大学生实践创新训练计划项目(201710300044Z)
中文摘要:利用1979-2015年降水观测资料、海表温度资料及NCEP/NCAR再分析资料,研究了南京夏季降水的时间变化规律,发现南京夏季降水具有明显的年际和年代际变化特征,且总体呈增多趋势。1991年南京夏季降水为极端正异常年份,距平为343.92 mm;1994年南京夏季降水为负异常年份,距平为-273.78 mm。南京夏季降水与副热带东北太平洋(美国加利福尼亚地区西海岸)海温异常存在显著的负相关关系,1991年副热带东北太平洋海温负异常,1994年副热带东北太平洋海温无显著异常。1991年副热带东北太平洋海温负异常,引起该地区上空低层辐散、高层辐合,热带中东太平洋上空低层辐合、高层辐散,这样的环流异常引起中东太平洋上空存在异常上升运动,该异常上升运动则通过纬向垂直环流引起菲律宾附近产生下沉运动并抑制该地区对流活动,激发出负位相的EAP/PJ型遥相关波列,引起了包括南京在内的长江流域降水正异常;同时,水汽由菲律宾地区向南京地区输送并辐合,有利于南京地区1991年夏季降水偏多。1994年副热带东北太平洋海温无显著异常,菲律宾附近对流活动活跃,激发出正异常的EAP/PJ型遥相关波列;同时,水汽由黑潮延伸区经日本列岛向西输送,南京地区为水汽辐散区域,使得1994年南京夏季降水负异常。
中文关键词:夏季  降水异常  南京  海表温度异常  副热带东北太平洋
 
Relationship of Nanjing summer precipitation anomaly and subtropical Northeast Pacific SSTA in 1991 and 1994 and its causes
Abstract:Based on the observed precipitation,sea surface temperature and NCEP/NCAR reanalysis data from 1979 to 2015,this paper analyzes temporal features of Nanjing summer precipitation.Results indicate that the precipitation has obvious interannual and interdecadal variations,with an overall increasing trend.In 1991,summer precipitation in Nanjing is an extremely positive anomaly,with the anomaly of 343.92 mm,while the precipitation in 1994 is a negative anomaly,with the anomaly of -273.78 mm.There is a significant negative correlation between summer precipitation in Nanjing and sea surface temperature anomaly(SSTA) in the subtropical Northeast Pacific(west coast of California,USA).SSTA in subtropical Northeast Pacific is negative in 1991 and no significant in 1994.The negative SSTA in the subtropical Northeast Pacific in 1991 causes the low-level divergence and high-level convergence over the region,and the low-level convergence and high-level divergence over the tropical Middle East Pacific.Such circulation anomalies cause abnormal upward motion over the Middle East Pacific Ocean.The abnormal upward motion causes sinking motion near the Philippines and inhibits convective activity in the region through zonal vertical circulation,triggers negative EAP/PJ teleconnection wave train,and causes positive precipitation anomalies in the Yangtze River basin,including Nanjing.At the same time,water vapor is transported and converged from Philippines to Nanjing,which is conducive to more precipitation in Nanjing in the summer of 1991.In 1994,there is no significant SSTA in the subtropical Northeast Pacific,and the convective activity near the Philippines is active,which triggers the positive anomalous EAP/PJ teleconnection wave train.Meanwhile,water vapor is transported westward from the Kuroshio extended area through the Japanese islands,and Nanjing region is a water vapor divergence area,which makes the summer precipitation in Nanjing negative anomaly in 1994.
keywords:summer  precipitation anomaly  Nanjing  sea surface temperature anomaly  subtropical Northeast Pacific
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