Correlation of topographic factors with precipitation and surface temperature in arid and cold region of Northwest China: a case study in Gansu Province
西北旱寒区地理、地形因素与降雨量及平均温度的相关性——以甘肃省为例

Topography is one of the most important factors affecting agricultural systems and ecological conservation in the arid and cold regions of Northwest China. In this study, the Gansu Province region was chosen to evaluate the correlation between monthly surface temperature/precipitation with latitude/longitude altitude/aspect and slope using the surface temperature and precipitation data of 1980, 1990 and 2000 across 122 meteorological stations using remote sensing and GIS techniques. The results showed that precipitation was popularly correlated with three large topographic factors, longitude, latitude and elevation, but had no significant correlation with slope and aspect; there was a significantly negative correlation between rainfall and latitude, with the average partial correlation coefficient of above 0.5. In addition, monthly surface temperature was observed to have a high negative correlation with longitude and altitude, where the partial correlation coefficient between surface temperature and elevation was more than 0.9, but the correlation of surface temperature with slope and surface temperature with aspect were not significant. Furthermore, we analyzed the correlations of monthly surface temperature with latitude across all the months of the three years, and found that the number of the months when a significant correlation between temperature and latitude was observed became fewer with the increase of years, while there was a correlation between them. Additionally, among the months in which the correlation was there, the partial correlation coefficient between temperature and latitude decreased year by year, suggesting that the effect of the latitude on the spatial distribution of temperature was gradually weakening. The results support the existing viewpoint that the extent of the arid northwest China has been extending to the south and east, and provide theoretical potential for arid agro-ecosystem management under global change.