Abstract: Based on the daily average air temperature of 83 meteorological stations over the three northeastern provinces in China during 1961 to 2014,the variation characteristics of annual mean air temperature,accumulated temperatures steadily above 0℃and 10℃ and their beginning and ending dates as well as lasting days were investigated using the statistical analysis methods such as climate tendency,cumulative anomaly curve and 9-year moving average.The results show that the thermal resources in the three provinces in recent 54 years are increasing with tendency rates of 0.29℃/10 a,60.10 (℃·d)/10 a,60.00 (℃·d)/10 a for annual mean air temperature,accumulated temperatures steadily above 0℃and 10℃,respectively.The tendency rates for the lasting days,beginning and ending dates of temperatures steadily above 0℃and 10℃ are 2.3 d/10 a and 1.9 d/10 a,-1.3 d/10 a and -0.8 d/10 a,1.0 d/10 a and 1.1 d/10 a,respectively.In addition,the increasing trends for heat resources in the three provinces are more significant in the north than in the south of the studied area.However,around 2005,the annual mean air temperature,the cumulative temperatures steadily above 0℃ and 10℃ and their lasting days are all decreasing gradually,while the beginning dates of temperatures steadily above 0℃ and 10℃ are delayed and their ending dates are ahead of time relatively.Besides,the increasing tendencies of thermal resources in the three provinces are slowing down from the south to north.

Key words: Thermal resources, Accumulated temperature, Lasting days, Climate tendency