Change characteristics of precipitation and temperature in the Qilian Mountains and Hexi Oasis, Northwestern China

Abstract

Precipitation and temperature in the Qilian Mountains and the Hexi oasis are changing with climate change. The characteristics and control factors of these changes are not well understood, affecting the ability to allocate water resources in this area judiciously. We analyzed the annual and seasonal variability in precipitation and temperature during 1960–2016 using monthly data from 25 national meteorological stations in the Qilian Mountains. Results showed that precipitation increased by 6.2, 4.1, and 8.9 mm/decade for the whole regions (including oasis and mountains), oasis, and mountains, respectively. Variability in summer precipitation made the greatest contribution to the annual change in precipitation. Moreover, the increment in precipitation was amplified with elevation. Enhanced westerly circulation and increased water vapor were the factors responsible for the increased precipitation in the study area. Temperature in the whole regions, oasis, and mountains increased at the rate of 0.32, 0.32, and 0.33 °C/decade, respectively. Changes in temperature were greatest in winter, with 0.47, 0.36 and 0.50 °C/decade in the whole regions, oasis, and mountains, respectively; changes in winter temperature made the greatest contribution to the annual temperature changes. Seasonal differences in carbon dioxide concentration may have caused the seasonal differences in the rate of temperature increase. The annual increase in temperature was mainly due to Siberian High, and Arctic Oscillation, carbon emissions and decreased cloud cover in the study area. The study results will help evaluate climatic hazards and contribute to development of water resources management strategies such as supplementary irrigation.