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Abstract:
Glaciers are prominent indicators for climate change, because they are sensitive to changes in temperature and precipitation. In contrast to this general behaviour, surge-type glaciers also experience mass redistributions independent of climate conditions. Many of these surge-type glaciers are concentrated in High-Mountain Asia, namely in the Karakoram and Pamir mountains.Here, recent surges of two neighbouring glaciers in the western Pamir Mountains are presented. Gando Glacier started its active surge phase in 2018, while its northern neighbour Sugran Glacier started surging in 2020. Optical and radar satellite data, e.g. Sentinel-2, ASTER and TanDEM-X have been used to describe the temporal evolution as well as the spatial extension of the surge. Gando Glacier started to accelerate on its southern branch with velocities increasing from about 1 m/d in spring to 6 m/d in autumn 2018, the observed peak of the surge. In the two following years, the velocities increased slightly again in late autumn. In 2019 the surge spread to the main glacier causing an elevation increase of more than 100 m at the confluence. Both the zone of higher velocities and of increased elevation propagated downstream consistently by about 7 km within four years, while upper reaches were affected by surface lowering. The surge of the northern neighbour Sugran Glacier is until now of smaller magnitude but not yet completed. The characteristics of both surges are discussed in terms of a possible surge mechanism.
