Annual mass balance time series for the Tien Shan and Pamir from 2000 to 2018

Annual mass time series for Central Asia were calculated using the transient snowline position and its rate of change during the ablation season to constrain the winter snow accumulation and the melt parameters of a distributed accumulation and temperature-index model for each glacier and year individually. This method is based on Barandun et al., 2018, TC and was regionally applied in Barandun et al., accepted, GRL (GRL mannuscript identifier: 2020GL092084). The transient snowline on a glacier marks the transition between the ice and snow surface, thus approximates the zero-mass balance line of the glacier during the ablation season. The snowline is hence a proxy for the surface mass balance. Automatic snowline mapping at the scale of individual glaciers on over 3,000 Landsat surface reflectance products provided a total of 255,000 snowlines from 2000 to 2018 for the region. As a second-order calibration, we calculated geodetic mass balances using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes and High Mountain Asia Digital Elevation Models (HMA DEMs). Our mass balance calculations, tied to transient snowline observations, provided annual mass balance time series for 1,222 (61%) glaciers greater than 2km2 located in the Tien Shan and Pamir. Details on the methods can be found in: Barandun, Martina, Matthias Huss, Ryskul Usubaliev, Erlan Azisov, Etienne Berthier, Andreas Kääb, Tobias Bolch, and Martin Hoelzle. "Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations." The Cryosphere 12, no. 6 (2018): 1899-1919. These annual time series have been presented in: Barandun, Martina, Eric Pohl, Kathrin Naegeli, Robert McNabb, Matthias Huss, Etienne Berthier, Tomas Saks and Martin Hoelzle. "Hot spots of glacier mass balance variability in Central Asia". Geophysical Research Letters, accepted (GRL mannuscript identifier: 2020GL092084).

本数据集针对中亚地区构建了年度冰川物质平衡时间序列，其计算基于消融季的瞬时雪线（transient snowline）位置及其变化速率，用以逐冰川、逐年约束分布式积累-温度指数模型（distributed accumulation and temperature-index model）的冬季积雪积累与冰川消融参数。该方法源自Barandun等人2018年发表于《冰冻圈（The Cryosphere）》的研究，并已在Barandun等人已接收的《地球物理研究快报（Geophysical Research Letters）》（GRL，手稿标识符：2020GL092084）中完成区域尺度应用。冰川上的瞬时雪线标志着冰面与雪面的分界，可近似代表消融季冰川的零物质平衡线，因此可作为冰川表面物质平衡的替代指标。本研究通过对超过3000景陆地卫星（Landsat）地表反射率产品开展单冰川尺度的自动雪线制图，最终获取了2000至2018年间该区域总计255000条雪线数据。作为二阶校准环节，本研究借助先进星载热发射与反射辐射计（Advanced Spaceborne Thermal Emission and Reflection Radiometer, ASTER）影像及喜马拉雅山地数字高程模型（High Mountain Asia Digital Elevation Models, HMA DEMs）计算了大地测量物质平衡（geodetic mass balances）。结合瞬时雪线观测约束的物质平衡计算，本研究为天山与帕米尔地区共计1222条面积大于2平方千米的冰川（占该区域对应冰川总数的61%）构建了年度物质平衡时间序列。相关方法细节可参阅以下文献：Barandun, Martina, Matthias Huss, Ryskul Usubaliev, Erlan Azisov, Etienne Berthier, Andreas Kääb, Tobias Bolch, and Martin Hoelzle. "Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations." *The Cryosphere* 12, no. 6 (2018): 1899-1919. 本数据集的年度时间序列结果已发表于：Barandun, Martina, Eric Pohl, Kathrin Naegeli, Robert McNabb, Matthias Huss, Etienne Berthier, Tomas Saks and Martin Hoelzle. "Hot spots of glacier mass balance variability in Central Asia". *Geophysical Research Letters*, accepted (GRL mannuscript identifier: 2020GL092084).