Rounce D R, Hock R, McNabb R W, Millan R, Sommer C, Braun M H, Malz P, Maussion F, Mouginot J, Seehaus T C, Shean D E
Department of Civil and Environmental Engineering Carnegie Mellon University Pittsburgh PA USA.
Geophysical Institute University of Alaska Fairbanks Fairbanks AK USA.
Geophys Res Lett. 2021 Apr 28;48(8):e2020GL091311. doi: 10.1029/2020GL091311.
Supraglacial debris affects glacier mass balance as a thin layer enhances surface melting, while a thick layer reduces it. While many glaciers are debris-covered, global glacier models do not account for debris because its thickness is unknown. We provide the first globally distributed debris thickness estimates using a novel approach combining sub-debris melt and surface temperature inversion methods. Results are evaluated against observations from 22 glaciers. We find the median global debris thickness is ∼0.15 ± 0.06 m. In all regions, the net effect of accounting for debris is a reduction in sub-debris melt, on average, by 37%, which can impact regional mass balance by up to 0.40 m water equivalent (w.e.) yr. We also find recent observations of similar thinning rates over debris-covered and clean ice glacier tongues is primarily due to differences in ice dynamics. Our results demonstrate the importance of accounting for debris in glacier modeling efforts.
冰面碎屑会影响冰川物质平衡，因为薄层会增强表面融化，而厚层则会减少表面融化。虽然许多冰川都被碎屑覆盖，但全球冰川模型并未考虑碎屑，因为其厚度未知。我们使用一种结合碎屑下融化和表面温度反演方法的新方法，首次给出了全球分布的碎屑厚度估计值。结果与22条冰川的观测数据进行了对比评估。我们发现全球碎屑厚度的中位数约为0.15±0.06米。在所有区域，考虑碎屑的净效应是平均使碎屑下融化减少37%，这可能对区域物质平衡产生高达0.40米水当量/年的影响。我们还发现，最近对碎屑覆盖冰川舌和清洁冰冰川舌类似变薄速率的观测，主要是由于冰动力学的差异。我们的结果证明了在冰川建模工作中考虑碎屑的重要性。
