Interannual Association of the Near-surface Temperature between Eastern China and the Arctic in Winter

Based on the NCEP/NCAR monthly reanalysis dataset and air temperature observations collected at 425 stations in China that is provided by the National Meteorological Information Centre, the spatial and temporal variations of the Siberian high and near-surface temperature over the Arctic and the middle-to-high-latitude region, and their direct and indirect interannual relationships with the air temperature over eastern China in the winter from 1956 to 2015 are explored using Empirical Orthogonal Function (EOF), correlation, and regression analyses, etc. For the above purpose, three Siberian high indexes are defined, including the Siberian high central intensity (SHCI), the Siberian high area (SHA) and the Siberian high eastern boundary (SHEB). The results show that the near-surface warming in the Barents-Kara Sea has rapidly increased in winter since 1998 and presents a significant negative interannual correlation with air temperature in eastern China. This relationship is named as the direct connection between the Arctic and eastern China in the present study. Meanwhile, the interannual associations between the above three indexes and the near-surface temperature over the Arctic and eastern China are significant in winter, suggesting that the Siberian high is a bridge linking the Arctic and East Asian climate to some extent. When the Arctic near-surface temperature increases (decreases), the intensity of the Siberian high enhances (weakens), its coverage expands (shrinks), its eastern boundary extends further eastward (retreats westward), and the temperature decreases (increases) in eastern China. The above relationship is called indirect connection between the Arctic and Eastern China in the present study. Finally, the possible physical mechanisms for the influences of Arctic near-surface temperature on eastern Asia temperature are discussed.