Connection between Spring Land Surface Thermal Anomalies over West Asia and Decadal Variation of Early Summer Cold Vortex in Northeast China

The cold vortex index in Northeast China is calculated by using the monthly station temperature data during 1979-2015 provided by the National Climate Center of China.In the present study, basic features of the cold vortex activity variation and its possible linkage with the springtime land surface thermal condition over west Asia are investigated.Results are as follows:(1) The intensity of the cold vortex in Northeast China displays a significant decadal fluctuation and an obvious decadal transition from positive phase (strong cold vortex) to negative (weak cold vortex) phase around 2000.(2) Decadal variation is also found in springtime land surface thermal condition over West Asia.The land surface was relatively cold before 2000 but became warm since then.(3) There is a close relationship between the decadal variations in early summer cold vortex and spring land surface thermal condition, i.e., cold (warm) land surface corresponds to intensified (weakened) cold vortex.Further analysis suggests that anomalous land surface thermal forcing can result in abnormal general circulation and affect the cold vortex activity via the atmospheric teleconnection.However, the related physical mechanism needs further investigation in the future.