Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction
Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction
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DOI：
10.5194/tc-9-151-2015
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发表时间：
2015-01-01
期刊：
影响因子：
5.2
通讯作者：
Grigoriev, M. N.
中科院分区：
文献类型：
--
作者：
Guenther, F.;Overduin, P. P.;Grigoriev, M. N.
利用当代甚高分辨率卫星和历史航空影像海岸线撤退的观测进行了比较，以测量开放水域的分数，夏季气温和风。我们分析了季节性和年际变化的解冻引起的悬崖顶部撤退（热剥蚀）和海洋磨损（热磨损）Muostakh岛在南部中央拉普捷夫海。地貌分析显示，穆奥斯塔赫的总地面冰含量由等量的沉积物内冰和宏观地面冰组成，总计达87%，使该岛特别容易受到沿着侵蚀，导致土地流失。基于实地活动期间的地形参考测量，我们使用立体摄影测量生成了数字高程模型，以便对1951年的航空照片和2010年至2013年的GeoEye，QuickBird，WorldView-1和WorldView-2图像进行块调整和正射校正，以进行变化检测。使用海冰浓度数据从特殊传感器微波成像仪（SSM/I）和空气温度时间序列从附近的Tiksi，我们计算了季节性的持续时间热磨损，表示为开放水域天，和热剥蚀，根据日平均气温为正值的天数。悬崖顶部退缩的季节动态显示，在2010-2013年的观测期间，盛夏的快速热剥蚀率为-10.2 +/- 4.5 m a（-1），沿海岸线的热磨蚀率为沿着-3.4 +/- 2.7 m a（-1），目前几乎是1951年以来平均速率-1.8 +/-1.3 m a（-1）的两倍。我们的研究结果表明，夏季平均气温和沿海热侵蚀率之间的密切关系，在协议的观测不同的东西伯利亚冰复杂的海岸在北极其他地方的各种永久冻土海岸线。海岸线退缩的季节性和环境因子的年际变化表明，热剥蚀和热磨蚀过程的持续时间的增加有利于更大的海岸侵蚀。在过去的62年里，海岸热侵蚀使该岛的面积减少了0.9平方公里（24%），但其体积却减少了28 × 10（6）立方米（40%），这不仅仅是因为永久冻土融化沉降，最明显的是在该岛快速侵蚀的北开普省附近的耶多马高地，其速率>= -11厘米/年。最近两者的加速发展将使穆奥斯塔赫岛的寿命减少一半，不到世纪。
Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fraction, summer air temperature, and wind. We analysed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermoabrasion) on Muostakh Island in the southern central Laptev Sea. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice and sums up to 87 %, rendering the island particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block-adjust and orthorectify aerial photographs from 1951 and GeoEye, QuickBird, WorldView-1, andWorldView-2 imagery from 2010 to 2013 for change detection. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from nearby Tiksi, we calculated the seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on the number of days with positive mean daily temperatures. Seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of -10.2 +/- 4.5 m a(-1) in mid-summer and thermo-abrasion rates along the coastline of -3.4 +/- 2.7 m a(-1) on average during the 2010-2013 observation period, currently almost twice as rapid as the mean rate of -1.8 +/- 1.3 m a(-1) since 1951. Our results showed a close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different to the East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality of coastline retreat and interannual variations of environmental factors suggest that an increasing length of thermo-denudation and thermo-abrasion process simultaneity favours greater coastal erosion. Coastal thermoerosion has reduced the island's area by 0.9 km(2) (24 %) over the past 62 years but shrank its volume by 28 x 10(6) m(3) (40 %), not least because of permafrost thaw subsidence, with the most pronounced with rates of >= -11 cm a(-1) on yedoma uplands near the island's rapidly eroding northern cape. Recent acceleration in both will halve Muostakh Island's lifetime to less than a century.