Spatio-temporal changes of ≥ 10°C accumulated temperature in northeastern China since 1961

The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air temperature of 1961–2009 from 106 meteorological stations in the northeastern China were chosen in this study. Using statistical methods and isoline method, the spatio-temporal changes of various decadal ≥ 10°C accumulated temperature and the climatic means of ≥ 10°C accumulated temperature were studied in this paper. The results showed that 1) The geographical distribution of ≥ 10°C accumulated temperature in the northeastern China could be influenced directly by the latitude, longitude and altitude. If latitude moved one degree northward, the average decrease amplitude of the climatic means was 101.9°C in the study area. 2) The means of decadal ≥ 10°C accumulated temperature rose since the 1980s, and their increase amplitudes became larger in the 1990s and the 2010s obviously. Compared with those of the 1980s, ≥ 10°C accumulated temperature increased by about 100°C in the mountainous and plain areas in the 1990s; compared with those of the 1990s, ≥ 10°C accumulated temperature increased by about 200°C in the Hulun Buir High Plain and the Songnen Plain, and 100°C in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3) The means of the decadal ≥ 10°C accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57°C/10yr in 1961–2009. 4) The climatic means of ≥ 10°C accumulated temperature increased from 1961–1990 to 1971–2000 and 1981–2009. Compared with the climatic mean of 1971–2000, that of 1981–2009 had increased by above 50°C in most of the study area, even up to 156°C. Compared with the climatic mean of 1961–1990, that of 1981–2009 increased by above 100°C in most parts of the study area, even up to 200°C. 5) The maximum northward shift, eastward and westward extension amplitudes of 3100°C, 3300°C and 3500°C isolines were larger among all isolines for the climatic means of the three phases. Compared with the positions of the isolines of 1961–1990, those amplitudes of 3100°C isoline of 1981–2009 were 145 km, 109 km and 64 km, respectively; those of 3300°C isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500°C isoline was about 100 km.