Abstract:

 Based on the daily average air temperature data at 165 meteorological stations in North and Northeast China from 1960 to 2010, the temporal and spatial variation characteristics of accumulated temperature steadily above 0 ℃ and 10 ℃, their lasting days, the beginning and ending dates were analyzed using a linear trend estimation method in order to find out the impact of climate warming on the distribution of thermal resources. The results show that the air temperature increases continuously in North and Northeast China, with an increasing trend of annual average air temperature of 0.32 ℃ per decade (P<0.001). It is well correlated with the other thermal resources indexes. The above 0 ℃ and 10 ℃ steady accumulated temperature and its lasting days increase significantly in North and Northeast China with climate warming, and the increasing trends for both are greater than 30 ℃·d per decade and 2 days per decade, respectively. The northern boundaries of subtropical zone and warm temperature zone move northward in North and Northeast China after 2000, especially the former. The northern limit of two-cropping systems moves northward obviously in Shanxi and Liaoning provinces after 1990s, and the mean moved distance exceeds 1.5 latitudes. The widespread increase of the above 0 ℃ and 10 ℃ steady accumulated temperature and their lasting days are influenced by advanced shift of the beginning date and backward shift of the ending date. Furthermore, the influence of the  advanced shift of the beginning date is more significant than that of the backward shift of the ending date for the above 0 ℃ steady accumulated temperature and lasting days, while both have similar influence for the above 10 ℃ steady accumulated temperature and lasting days.

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