Snow recurrence sets the depth of dry permafrost at high elevations in the McMurdo Dry Valleys of Antarctica
Snow recurrence sets the depth of dry permafrost at high elevations in the McMurdo Dry Valleys of Antarctica
复制标题
积雪的复发决定了南极洲麦克默多干谷高海拔地区干燥永久冻土的深度
作者：
C. Mckay
地球上干燥的永久冻土是南极特有的，在麦克默多干谷的高海拔地区发现。尽管它在干谷中广泛存在，但控制干燥永久冻土及其下方冰固化地面分布的因素却知之甚少。在这里，我通过理论分析和实地观察相结合，表明雪的复发可以解释南极洲干燥永久冻土的深度和冰固化地面的位置。对于赖特谷上游海拔1600-1650米的林奈台地的数据来说，大约两年的重复周期解释了25厘米深、12.5厘米干永久冻土层下地面冰的存在。超过10年的积雪复发周期只会在这个地点造成干燥的永久冻土。大学谷的雪梯度是由极地高原的风吹雪形成的，在深度上形成了相应的冰固化地面梯度。在Beacon Valley的底部，没有下垫冰的干燥永久冻土层的存在表明积雪的复发间隔超过10年，这表明该山谷的古代大块冰并不稳定。雪的反复出现也可能使火星上的地面冰深度增加。
Abstract Dry permafrost on Earth is unique to the Antarctic and is found in the upper elevations of the McMurdo Dry Valleys. Despite its widespread presence in the Dry Valleys, the factors that control the distribution of dry permafrost and the ice-cemented ground below it are poorly understood. Here I show, by a combination of theoretical analysis and field observations, that the recurrence of snow can explain the depth of dry permafrost and the location of ice-cemented ground in Antarctica. For data from Linnaeus Terrace at 1600–1650 m elevation in Upper Wright Valley a recurrence intervals of about two years explains the presence of ground ice at 25 cm depth, under 12.5 cm of dry permafrost. Snow recurrence periods longer than 10 years would create only dry permafrost at this site. The snow gradient in University Valley resulting from the windblown snow from the polar plateau creates a corresponding gradient in the depth to ice-cemented ground. On the floor of Beacon Valley, the presence of dry permafrost without underlying ice-cemented ground indicates snow recurrence intervals of more than 10 years and implies that the ancient massive ice in this valley is not stable. Snow recurrence may also set the depth to ground ice on Mars.