Changes of China agricultural climate resources under the background of climate change. III. Spatiotemporal change characteristics of agricultural climate resources in Northwest Arid Area

By using the 1961-2007 daily weather data from 78 meteorological stations in Northwest Arid Area, this paper analyzed the spatiotemporal characteristics of agricultural climate resources, i.e., heat, light, and precipitation, in the area, both in the whole year and in temperature-defined growth seasons of chimonophilous and thermophilic crops. In 1961-2007, the mean annual temperature in the area had an increasing trend, and the climate tendency rate was 0.35 degrees C x (10 a)(-1). The accumulated temperature in temperature-defined growth seasons of both chimonophilous and thermophilic crops also had an increasing trend, and the climate tendency rate was 67 and 50 degrees C d x (10 a)(-1), respectively. The annual sunshine hours in most stations of the research area had an obvious decreasing trend, but the sunshine hours during the temperature-defined growth seasons of chimonophilous and thermophilic crops had an increasing trend, except that in most regions of Xin-jiang and east Ningxia Plain. The annual reference evapotranspiration in most regions of the study area tended to decrease, while the reference evapotranspiration during temperature-defined growth seasons of chimonophilous and thermophilic crops tended to decrease in the west but increase in the east. Compared with that in 1961-1980, the precipitation both in the whole year and in temperature-defined growth seasons of chimonophilous and thermophilic crops in 1981-2007 increased, and the increment reduced progressively from the northwest to the southeast.