The Response of Annual Runoff to the Height Change at the Zero Temperature Level in Summer over Xinjiang
新疆夏季0 oC 层高度变化对河流年径流量的影响

Xinjiang is divided into three regions: the Altay Mountains-Tacheng, the Tianshan Mountains and the northern slope of the Kunlun Mountains by the climatic feature and their runoff. Based on the daily observed materials from 12 air sounding meteorological stations and the annual runoff materials from 34 hydrological stations during the period of 43 years from 1960 to 2002, the mean height change at the 0 oC level, the changing trend of runoff and their deviation of spacial distribution were researched in Xinjiang according to the methods of the combination of qualitative and quantitative analyses and the contrast with the five-year smoothing mean curve. The results show that there exists a better coherence between the height change at the 0 oC level and the annual runoff amount of the rivers in Xinjiang, and this kind of correlation has especially turned closer since 1970. Each region had its own unique feature that the heights have been significantly ascending over Altay Mountains-Tacheng and Tianshan Mountains, and that the height has been lowering over the northern Kunlun Mountains since 1990. Correspondingly the runoff over the former two regions has been increasing and over the latter has been slightly decreasing in the same period of time. In terms of relativity, there exist better linear correlations at the significance level of 0.01 between the height at the 0 oC level in summer and the runoff over Xinjiang as well as the Tianshan Mountains and the northern slope of the Kunlun Mountains. Recently, the height change at the 0 oC level has been resulted not only from the climate change on the ground but also from the upper climate change in Xinjiang. Along with the climate warming, the ascend of the height at the 0 oC level and the increase of melting snow in mountains, the runoff is accordingly gaining so that Xinjiang is witnessing the period of abundant water, and vice versa. So the runoff is directly resulted from the lifting of the height at the 0 oC level in summer. The increase of temperature in the upper air is one of the immediate factors during the course that the climate in Xinjiang is getting warmer and wetter.