Spatio-Temporal Changes Of >= 10a Degrees 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 a parts per thousand yen 10A degrees C accumulated temperature and the climatic means of a parts per thousand yen 10A degrees C accumulated temperature were studied in this paper. The results showed that 1) The geographical distribution of a parts per thousand yen 10A degrees 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 101.9A degrees C in the study area. 2) The means of decadal a parts per thousand yen 10A degrees 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, a parts per thousand yen 10A degrees C accumulated temperature increased by about 100A degrees C in the mountainous and plain areas in the 1990s; compared with those of the 1990s, a parts per thousand yen 10A degrees C accumulated temperature increased by about 200A degrees C in the Hulun Buir High Plain and the Songnen Plain, and 100A degrees C in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3) The means of the decadal a parts per thousand yen 10A degrees C accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57A degrees C/10yr in 1961-2009. 4) The climatic means of a parts per thousand yen 10A degrees 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 50A degrees C in most of the study area, even up to 156A degrees C. Compared with the climatic mean of 1961-1990, that of 1981-2009 increased by above 100A degrees C in most parts of the study area, even up to 200A degrees C. 5) The maximum northward shift, eastward and westward extension amplitudes of 3100A degrees C, 3300A degrees C and 3500A degrees 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 3100A degrees C isoline of 1981-2009 were 145 km, 109 km and 64 km, respectively; those of 3300A degrees C isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500A degrees C isoline was about 100 km.