Abstract:Based on the NCEP/NCAR reanalysis data,the spatial-temporal characteristics of surface temperature over Eurasia in wintertime are investigated.It is found that,on both interdecadal and interannual scales,the ground temperature variation in the north of Eurasian continent has obviously opposite characteristics compared with that in the south.Especially,the anti-phase relation has a clear phase-locking trend over 16-yr period.Thus,a land thermal contrast(LTC) index is defined in this paper and the relation between LTC index and atmospheric circulation is further investigated.Results show that the LTC index is closely related to the anomalous variations of mid-latitude westerly strength at 500 hPa,East Asian trough and southern westerly trough.When the temperature is cold in the north and warm in the south of Eurasia(i.e.during the positive phase years of LTC index),500 hPa middle latitude westerlies strengthen,East Asian trough deepens and moves westward,and southern westerly trough weakens,and vice versa.