Relationship between Asian Circulation in the Middle-High Latitude and Snowfall over South China during La Nia Events
ZHANG Qing-Yun1,2,XUAN Shou-Li2,3,and PENG Jing-Bei21 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 1000292 Center for Disastrous Climate Research and Prediction,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 1000293 Graduate University of Chinese Academy of Sciences,Beijing 100049
The moderate-strong La Nia was throughout in boreal winter 2007-2008 year,and the anomalous snowfall and extreme low temperature occurred in South China during January 2008.The Asian Circulation in middle-high latitude and association with the aspect of snowfall in South China during La Nia events were studied based on NCAR/NCEP reanalyzed dataset.It had been found that there was a blocking pattern in Asian Circulation of middle-high latitude at 500 hPa during La Nia events.When the intensity of blocking pattern over Ural Mountains was stronger than over Okhotsk Sea in January during La Nia years,the temperature in South China was lower than normal and there was association with heavy snowfall due to the northerly wind in South China was related with the circulation in Ural Mountains.When the intensity of blocking pattern over Okhotsk Sea was stronger than over Ural Mountain in January during La Nia years,the temperature in South China was above normal and association with a light snowfall due to the northerly wind in South China was connected with the circulation in Okhotsk Sea.In January 2008,the intensity of blocking pattern over Ural Mountain looks more strengthened(positive anomalous 120 gpm).There were two branchs northerly wind in South China,and both of them were associated with the circulation from Ural Mountain which resulted in the colder air temperature in South China.The intensity of southern branch jet stream over Southern Asia at 200 hPa and its association with the snowfall in South China during La Nia events were also discussied.
【Fund】： 中国科学院大气物理研究所创新基金领域前沿重点项目IAP07120;; 中国科学院知识创新工程重要方向项目KZCX3-SW-226
【CateGory Index】： P448
【CateGory Index】： P448