格陵兰冰盖渗流区杉木层的吸热和传热

IF 3.5 2区 地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY
Jun Saito, Joel Harper, Neil Humphrey
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引用次数: 0

摘要

格陵兰冰原(GrIS)枞树层内的热场控制着融水滞留过程、枞树密度随地表高程变化的变化以及从地表边界到深冰的热传递。然而,用于制约这些过程的观测数据很少,只有稀疏的原地温度时间序列,而且没有延伸到整个枞树层深度。在此,我们利用安装在延伸至 30 米和 96 米深度的钻孔高程横断面上的仪器,量化了格陵兰西部杉柱的热结构。在2019年高融度夏季,杉林层的热增量显示出强烈的海拔依赖性,海拔越低,热量吸收越多,渗透越深。由于冰层密度较高,每降低 100 米海拔,体导热率增加 15%。尽管如此,由于海拔较高处近地表枞树层的温度梯度较大,沿横断面的导热增量仍保持相对稳定。在这个高融化度的夏季,热增量的主要驱动因素是潜热传递,它在横断面上增加了 10 倍,每降低 100 米海拔增加 34 兆焦耳/米-2。在研究断面上,季节性活跃层下的深厚杉层温度梯度在海拔下降 270 米时增加了一倍,增加了从杉层进入低海拔深厚冰层的热通量。我们的原地杉木温度时间序列为建模研究提供了观测约束,并为未来气候变暖时渗流区的演变提供了启示。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Uptake and Transfer of Heat Within the Firn Layer of Greenland Ice Sheet's Percolation Zone

Uptake and Transfer of Heat Within the Firn Layer of Greenland Ice Sheet's Percolation Zone

The thermal field within the firn layer on the Greenland Ice Sheet (GrIS) governs meltwater retention processes, firn densification with surface elevation change, and heat transfer from the surface boundary to deep ice. However, there are few observational data to constrain these processes with only sparse in situ temperature time series that does not extend through the full firn depth. Here, we quantify the thermal structure of Western Greenland’s firn column using instrumentation installed in an elevation transect of boreholes extending to 30 and 96 m depth. During the high-melt summer of 2019, heat gain in the firn layer showed strong elevation dependency, with greater uptake and deeper penetration of heat at lower elevations. The bulk thermal conductivity increased by 15% per 100 m elevation loss due to higher density related to ice layers. Nevertheless, the conductive heat gain remained relatively constant along the transect due to stronger temperature gradients in the near surface firn at higher elevations. The primary driver of heat gain during this high melt summer was latent heat transfer, which increased up to ten-fold over the transect, growing by 34 MJ m−2 per 100 m elevation loss. The deep-firn temperature gradient beneath the seasonally active layer doubled over a 270-m elevation drop across the study transect, increasing heat flux from the firn layer into deep ice at lower elevations. Our in situ firn temperature time series offers observational constraints for modeling studies and insights into the future evolution of the percolation zone in a warmer climate.

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来源期刊
Journal of Geophysical Research: Earth Surface
Journal of Geophysical Research: Earth Surface Earth and Planetary Sciences-Earth-Surface Processes
CiteScore
6.30
自引率
10.30%
发文量
162
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