The Qinghai-Tibet Plateau is sensitive to global climate change because of its special geographical environment.Therefore,analyzing the temporal dynamics and spatial patterns of surface freeze-thaw cycles and vegetation green-up date to determine and predict their response to global climate change is important.A dual-index algorithm is adopted to obtain long-term series of surface freeze-thaw states from passive microwave brightness temperatures observed by SMMR,SSMI,and SSMIS during 19822013.The vegetation green-up date during 19822013 is derived based on the reconstructed NDVI from the GIMMS global vegetation index dataset by the filter algorithm.On the basis of both datasets,the areal extent,timing,seasonal variations,and inter-annual trend of surface soil freeze-thaw cycles and vegetation green-up date are examined across the Qinghai-Tibet plateau via regression and correlation analyses.Most pixels on the images of the Qinghai-Tibet Plateau showed the frozen state from October 30 to April 2 of the subsequent year.The average start date of surface thawing occurred mainly from May 12 to May 27,and the average green-up date occurred from May 19 to May 29.The green-up date occurred 3.945.58 days after the start date of surface thawing on the average,and a significant correlation exists between them (R=0.51,P=0.003).The trends for the start date of surface thawing and green-up date underwent three stages,namely,delay,advance,and delay,from 1982 to 2013.The start date of surface thawing and the green-up date were delayed at speeds of 1.931.81 and 0.281.01 days/year from 1982 to 1987,advanced at speeds of 0.670.20 and 0.130.16 days/year from 1987 to 2006,and delayed at speeds of 0.970.84 and 1.040.52 days/year from 2006 to 2013,respectively.However,the meteorological stations operated by the China Meteorological Administration indicated that the 0 cm ground surface temperature presented a continuous increasing trend,which might be caused by the changes in other environmental factors,such as heterogeneous precipitation on the Qinghai-Tibet Plateau.At the same time,the temperature threshold of vegetation green-up date showed a continuous upward trend (R=0.72,P<0.001) as air temperature increased,which was possibly correlated to the capability of vegetation to self-adapt to climate change.