Rock debris covers ~30% of glacier ablation areas in the Central Himalaya and modifies the impact of atmospheric conditions on mass balance. The thermal properties of supraglacial debris are diurnally variable but remain poorly constrained for monsoon-influenced glaciers over the timescale of the ablation season. We measured vertical debris profile temperatures at 12 sites on four glaciers in the Everest region with debris thickness ranging from 0.08 to 2.8 m. Typically, the length of the ice ablation season beneath supraglacial debris was 160 days (15 May to 22 October)—a month longer than the monsoon season. Debris temperature gradients were approximately linear (r2 > 0.83), measured as −40°C m–1 where debris was up to 0.1 m thick, −20°C m–1 for debris 0.1–0.5 m thick, and −4°C m–1 for debris greater than 0.5 m thick. Our results demonstrate that the influence of supraglacial debris on the temperature of the underlying ice surface, and therefore melt, is stable at a seasonal timescale and can be estimated from near-surface temperature. These results have the potential to greatly improve the representation of ablation in calculations of debris-covered glacier mass balance and projections of their response to climate change.

中文翻译：

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喜马拉雅中部尼泊尔珠穆朗玛峰地区冰川上碎片的季节性稳定温度梯度

岩石碎片覆盖了喜马拉雅中部约 30% 的冰川消融区域，并改变了大气条件对物质平衡的影响。冰上碎片的热特性是昼夜变化的，但在消融季节的时间尺度上，受季风影响的冰川的限制仍然很差。我们测量了珠穆朗玛峰地区四个冰川上 12 个地点的垂直碎片剖面温度，碎片厚度从 0.08 到 2.8 m。通常，冰上碎片下的冰消融季节的长度为 160 天（5 月 15 日至 10 月 22 日）——比季风季节长一个月。碎片温度梯度近似线性（r2> 0.83)，测量为 -40°C m–1碎屑厚达 0.1 m，-20°C m–1适用于 0.1–0.5 m 厚和 -4°C m 的碎屑–1对于厚度大于 0.5 m 的碎屑。我们的研究结果表明，冰上碎片对下伏冰面温度的影响以及融化的影响在季节性时间尺度上是稳定的，并且可以从近地表温度进行估计。这些结果有可能极大地改善消融在计算碎片覆盖的冰川质量平衡和预测它们对气候变化的反应中的表现。