1620 / 2019-08-23 11:18:23

Study on the Equilibrium Line Altitude Based on Multi-source Remote-Sensing Data of Urumqi Glacier No. 1 in Tienshan, China

15、冰冻圈科学 > 专题9：冰冻圈遥感与信息

The equilibrium line altitude (ELA) is an indicator which can reflect the change of the glacier mass balance. At the same time, the end-of-summer snow line can be considered as an indicator of ELA, which can be easily identified on satellite images acquired during the ablation season. Datasets of the satellite images acquired by Landsat TM/ETM/OLI and Sentinel-2A MSI were used to deduce snow line variability during 2002-2018 and derive equilibrium line altitude. Here, taking the Urumqi Glacier No. 1 in Tienshan in China as an example, the glacier equilibrium line altitude is derived from the Normalized Difference Snow Index (NDSI) method and threshold setting. The credibility of the equilibrium line altitude obtained from satellite images was analyzed using glacier annual mass balance calculated from field measurements and meteorological data. The results show that during 2002-2018, the overall trend of ELA derived from remote-sensing data is generally increasing; during 2002-2015, ELA is highly correlated with the ELA obtained from ground measurements (r=0.9). ELA has a high correlation with the annual mass balance sequence, and the average interpretation rate of the mass balance fluctuation can be as high as 69%; Correlation with the inter-annual variability of meteorological elements (temperature and precipitation) is also high, and about 59% of glacial ELA changes can be explained by summer temperature. Therefore, remote sensing data can be used to extract the glacier equilibrium line altitude, and then used to estimate the equilibrium line altitude and mass balance of glaciers where no ground measurements exist, especially for the estimation of small-scale glacier mass balance, it has certain reference significance.