A new inventory of High Mountain Asia surging glaciers derived from multiple elevation datasets since the 1970s

Abstract

Glacier surging is an unusual instability of ice flow, and inventories of surging glaciers are important for regional glacier mass balance studies and glacier dynamic studies. Glacier surges in High Mountain Asia (HMA) have been widely reported. However, the completeness of available inventories of HMA surging glaciers is hampered by the insufficient spatial and temporal coverage of glacier change observations or by the limitations of the identification methods. In this project, we established a new inventory of HMA surging glaciers based on glacier surface elevation changes and morphological changes over four decades. Three elevation change observations based on four elevation sources (the KH-9 DEM, NASA DEM, COP30 DEM, and HMA DEM), three publicly released datasets, and long-term Landsat satellite image series were utilized to assess the presence of typical surging features over two time periods (1970s–2000 and 2000–2020). Through a multi-criteria and cross-validation workflow, all surging glaciers within HMA were identified and indicated with different possibility of surging. Particular efforts were taken to exclude advancing glaciers and separate surging tributaries from glacier complexes. In total, 890 surging and 336 probably or possibly surging glaciers were identified in HMA. Compared to the most recent inventory of surging glaciers in HMA, our inventory incorporated 253 previously unidentified surging glaciers, and most of them are quite small glaciers due to the more complete coverage. The number and area of surging glaciers accounted for ∼ 2.49 % (excluding glaciers smaller than 0.4 km2) and ∼ 16.59 % of the total glacier number and glacier area in HMA, respectively. Glacier surges were found in 21 of the 22 subregions of HMA (except for the Dzhungarsky Alatau); however, the density of surging glaciers is highly uneven. Glacier surges occur frequently in the northwestern subregions (e.g., Pamir and Karakoram) but less often in the peripheral subregions. The inventory further shows that surge activity is more likely to occur for glaciers with a larger area, longer length, and wider elevation range. Among glaciers with similar areas, the surging ones usually have steeper slopes than non-surging ones. Finally, we leverage 50 years of multi-temporal glacier mass balance observations to investigate the relationship between glacier surges and mass balance.