Snow dynamics play a crucial role in the hydrology of alpine catchments in the Himalaya. However, studies based on in-situ observations that elucidate the energy and mass balance of the snowpack at high altitude in this region are scarce. In this study, we use meteorological and snow observations at two high-altitude sites in the Nepalese Himalaya to quantify the mass and energy balance of the seasonal snowpack. Using a data driven experimental set-up we aim to understand the main meteorological drivers of snowmelt, illustrate the importance of accounting for the cold content dynamics of the snowpack, and gain insight into the role that snow meltwater refreezing plays in the energy and mass balance of the snowpack. Our results show an intricate relation between the sensitivity of melt and refreezing on the albedo, the importance of meltwater refreezing, and the amount of positive net energy used to overcome the cold content of the snowpack. The net energy available at both sites is primarily driven by the net shortwave radiation, and is therefore extremely sensitive to snow albedo measurements. We conclude that, based on observed snowpack temperatures, 21% of the net positive energy is used to overcome the cold content build up during the night. We also show that at least 32–34% of the snow meltwater refreezes again for both sites. Even when the cold content and refreezing are accounted for, excess energy is available beyond what is needed to melt the snowpack. We hypothesize that this excess energy may be explained by uncertainties in the measurement of shortwave radiation, an underestimation of refreezing due to a basal ice layer, a cold content increase due to fresh snowfall and the ground heat flux. Our study shows that in order to accurately simulate the mass balance of seasonal snowpacks in Himalayan catchments, simple temperature index models do not suffice and refreezing and the cold content needs to be accounted for.

积雪动力学在喜马拉雅山高山流域的水文学中起着至关重要的作用。但是，基于现场观测的研究无法阐明该地区高海拔雪堆的能量和质量平衡。在这项研究中，我们使用尼泊尔喜马拉雅山两个高空站点的气象和降雪观测来量化季节性积雪的质量和能量平衡。使用数据驱动的实验装置，我们旨在了解融雪的主要气象驱动因素，阐明说明积雪的冷含量动态的重要性，并深入了解融雪融水在能量和质量平衡中的作用。的积雪。我们的结果表明，在反照率上，融化的敏感性与再冻结的敏感性之间存在复杂的关系，重新融化冰水的重要性，以及用于克服积雪的低温成分的正净能量的数量。两个站点的可用净能量主要由净短波辐射驱动，因此对雪反照率测量极为敏感。我们得出的结论是，根据观测到的积雪温度，将21％的净正能量用于克服夜间积聚的冷气。我们还显示，至少有32％到34％的积雪融水再次冻结了这两个地点。即使考虑了冷量和重新冻结，仍然可以使用多余的能量来融化积雪。我们假设这种过剩的能量可能是由于短波辐射测量的不确定性，由于基础冰层导致的重新冻结的低估，由于新鲜的降雪和地面热通量，冷含量增加。我们的研究表明，为了准确模拟喜马拉雅流域的季节性积雪的质量平衡，简单的温度指数模型不足以实现重新冻结，因此需要考虑冷量。