Climate variation and glacier response in the Bogda region, Tianshan Mountains

Abstract

Under the background of global warming in recent decades, glaciers on Earth have been rapidly melting. Mountain glaciers in China have also changed dramatically. The changes in mountain glaciers have impacts on water resources in the northwestern arid area of China, and therefore monitoring change of mountain glaciers is very important. The glacier meltwater in the Bogda Peak region is a reliable source of water for the Aries River Basin, the Turpan-Hami Basins, and Basin Chaiwopu, and the scientific value of such research is also significant. This article summarizes the status of research on this subject. Based on the 1972 Landsat MSS, 1990 Landsat TM, 1999 Landsat TM, and 2013 Landsat ETM+ remote sensing data, glacier information of four time periods in the study area were extracted by using visual interpretation combined with digital processing of satellite images and analysis in GIS. The climate data in the surrounding area were analyzed using linear regression,Mann-Kendall abrupt test, and Morlet wavelet analysis. The relationship between glacier retreating and climate warming was also analyzed in this study. The main results show that:(1) The annual mean temperature and precipitation had an increasing trend, with rates of 0.19℃·10a-1and 12.4mm·10a-1; annual temperature increased since 1990, while annual precipitation increased since 1985. Morlet wavelets of annual temperature mainly had a8 to 10 year cycle, while annual precipitation cycle was not clear. The warming trend was clear in this region, but rainfall has shown little change.(2) During 1972-2013, glacier area of the study region decreased by 46.71±1.32km2, accounting for 23.87 ± 0.67% of the total. The average annual withdrawal rate was 0.66 ± 0.02%·a-1. Glacier retreat rate was low in 1972-1990, at 0.44 ± 0.03%·a-1. But this rate has increased in the last 20 years, to0.78 ±0.09 %·a-1. The retreat rates of Sigonghe No.4 glacier and Black Trench No.8 glacier have accelerated in recent years.(3) Characteristics of the spatial structure of the glaciers were analyzed based on the fractal theory and the research predicts that the ablation rate of glaciers in the study area will remain high.(4) Compared with glacier retreat in other regions of China, glaciers in the Bogda area show a similar trend of change.(5) Prior to1990, the important meteorological factors that influenced the change of Bogda region glaciers were temperature and precipitation, but temperature has played a more important role in affecting glacier retreat after 1990.