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首页> 外文期刊>Permafrost and Periglacial Processes >Long-term field measurements of climate-induced thaw subsidence above ice wedges on hillslopes, western Arctic Canada
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Long-term field measurements of climate-induced thaw subsidence above ice wedges on hillslopes, western Arctic Canada

机译：气候诱导的冰楔上的气候诱导的解冻沉降的长期田间测量在北极加拿大西部的冰雪窗上

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摘要

Near-surface wedges of massive ice commonly outline polygons in tundra lowlands, but such polygons have been difficult to identify on hillslopes because soil movement flattens the ridges and infills the troughs that form beside and above the ice wedges. Over the past three decades, the active layer has thickened near the western Arctic coast of Canada and consequent thawing of ice wedges has been detected by remote sensing for flat terrain but not, generally, on hillslopes. Annual field surveys (1996-2018) at the Illisarvik field site of thaw depth and ground surface elevation show the mean subsidence rate above hillslope ice wedges has been up to 32 mm a(-1) since thaw depth reached the ice-wedge tops in 2007. Annual mean ground temperatures at the site are about -3.0 degrees C beneath late-winter snow depths characteristic of the ice-wedge troughs but about -5.3 degrees C under conditions of the intervening polygons. The rate of thaw subsidence is high for natural, subaerial disturbances because meltwater from the ice wedges runs off downslope. The rate is constant, because the thickness of seasonally thawed ground above the ice wedges and the ice content of the ground remain the same while the troughs develop. Observations of changes in surface elevation in northern Banks Island between the late 1970s and 2019 show troughs on hillslopes where none was previously visible. Development of these troughs creates regional thermokarst landscapes, distinct from the widely recognized results of thawing relict glacier ice, that are now widespread over Canada's western Arctic coastlands. Recognition of ice-wedge occurrence and accelerated thaw subsidence on hillslopes is important in the design of infrastructure proposed for construction in rolling permafrost terrain.
机译：寒云普通冰常见的近楔形覆盖在苔原低地的近地楔形，但这种多边形难以识别山坡上，因为土壤运动会使脊平稳，并填充冰楔旁边形成的低谷。在过去的三十年中，加拿大西北北极海岸附近的活跃层已经加厚，并通过遥感的平坦地形来检测到冰楔的解冻，但通常在山坡上。在解冻深度和地面仰角的Illisarvik现场的年场调查（1996-2018）显示山坡冰盖上方的平均沉降率高达32毫米A（-1），因为解冻深度达到了冰楔上面2007年。现场的年平均地下温度约为-3.0摄氏度，下冬天的雪深度冰楔的特征，但在介入多边形的条件下约为-5.3摄氏度。沉降率为自然的沉降率高，因为来自冰楔的熔融水越下熔融水。该速率是恒定的，因为在冰楔上方的季节性解冻地的厚度和地面的冰含量保持不变，而在槽的发展中仍然相同。 20世纪70年代后期和2019年北部银行岛屿面积仰角变化的观察山坡上的山坡展示山坡上的山坡上。这些低谷的发展造成了区域热态度的景观，不同于解冻贪婪冰川冰的广泛认可的结果，现在普遍存在加拿大的西部北极海岸。对山坡上的冰楔的识别和加速解冻沉降在滚动永久冻土地形建设的基础设施设计中非常重要。

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