Relationship between the interannual variations of Arctic sea ice and summer Eurasian teleconnection and associated influence on summer precipitation over China

This work investigates the relationship between Eurasian mid-high latitudes teleconnection in summer and the interannual variations of Arctic sea ice concentration (SIC) from preceding spring to summer and the associated influence on East Asian summer precipitation during the period of 1980-2015 by using NCEP/NCAR reanalysis datasets and the Community Atmospheric Model version 3. 1. Results show that the second Empirical Orthogonal Function mode of the summer 500 hPa geopotential height field over mid-high latitudes of the North Atlantic-Eurasian continent shows a clear "-+-+" pattern with an anomalous trough over the region from Greenland to the North Atlantic, Ural Mountains, and a anomalous ridge over Europe and regions around Lake Baikal, which is similar to the Eurasian (EU) teleconnection pattern. When the summer Eurasian teleconnection exhibits a "-+-+" ("-+-+") pattern, the light (heavy) SIC occurs in regions over Northern Barents Sea and Baffin Bay in preceding spring and over Northern Barents Sea in simultaneous summer, leading to deficit ( excessive) summer precipitations over most regions to north of the Yangtze River valley, especially northern Northeast China and the region between Yellow and Yangtze River valleys. Further study shows that the persistence of light SIC tends to change the local surface turbulent heat flux from spring to summer, triggering the anomalous Rossby wave sources and the propagation of quasi-stationary Rossby wave activity flux southward and eastward from Arctic to East Asia. These physical processes ultimately result in the development of anomalous summer Eurasian teleconnection. In addition, corresponding to the influence of light SIC condition, the "-+" dipole pattern of anomalous Eurasian snow water equivalent (SWE) in April-May is observed from the Ural Mountains to north of Lake Baikal. This dipole SWE pattern then changes the soil moisture and associated heat flux anomalies in the following summer, further resulting in the enhancement of the summer Eurasian teleconnection. Accompanying with occurrence of the "-+-+" Eurasian teleconnection, the Ural blocking and the East Asian trough are weakened. Meanwhile, the summer Asian subtropical jet stream is accordingly accelerated, with increase of the westerly wind over subpolar regions and decreasing to the north of the East Asian subtropical jet stream. This favors formation of anomalous anticyclonic circulation in south of Lake Baikal, leading to weaker cold air activities. The aforementioned circulation system ultimately results in deficit of summer precipitation in northern Northeast China and the regions between Yellow and Yangtze River valleys. Relative to heavy SIC conditions, the influences are inversed. On the basis of the spring SIC index and late spring SWE index, we also establish a prediction model for the summer precipitation in the Yangtze-Huaihe River valley. The hind-cast results show that our prediction model can well predict the variation of summer precipitation in the Yangtze-Huaihe River valley.