Modelling present glacier dynamics on Svalbard - from inferringsurface velocities to computing a flow-consistent bedrock map

对斯瓦尔巴群岛现有冰川动力学进行建模 - 从推断表面速度到计算流动一致的基岩图

• 批准号: 274939856
• 负责人: Dr. Johannes Fürst
• 金额: --
• 依托单位: Norwegisches Polarinstitut
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/274939856?language=en
• 关键词: Modelling; present; glacier; dynamics; Svalbard

Global surface temperatures have risen by ~0.7°C over the previous century. Due to an inherent amplification of climatic changes in high latitudes, warming has been more expressed in Polar Regions. One eminent consequence is the general retreat of Svalbard glaciers observed throughout the last century. In the last decades, southern Svalbard glaciers have even moved on to thin at dramatically increasing rates. This latest thinning trend is however not confirmed throughout the Arctic. The reason relies in the unique climatic conditions on Svalbard. Since warm ocean currents in the North Atlantic reach the southern tip of the archipelago, the climate is rather warm and variable for its latitudinal band. Evolution of Svalbard glaciers has therefore often been suggested to play a precursor role for the other Arctic regions.Within the Arctic, Svalbard is unique in another respect, as glacier extents and elevation changes are well characterised over several decades. However, the interpretation of these geometric changes in terms of the climatic evolution is inhibited, as they arise from both the climatic surface mass balance and from ice flow divergence. The latter depends on glacier geometry and dynamics, and is not necessarily directly controlled by changes in climatological parameters. Yet, observations on glacier thicknesses and velocities are sparse and temporally incoherent, which impedes to this day a reliable quantification of the dynamic control on Svalbard glacier changes. By extension, we have only a vague idea on how much volume is annually discharged by iceberg calving at the marine ice fronts. Ice discharge presumably explains a large portion in the total mass budget, as more than half of the ice-covered area drains through marine-terminated glaciers.The aim of the research proposal is to expand the knowledge on the ice dynamic component of glacier evolution to the entire Svalbard archipelago. To this end, surface velocities are inferred from satellite remote sensing, which, in turn, serve to reconstruct the bedrock topography beneath all ice-covered areas. The reconstruction makes use of the mass conservation principle, provides therefore a flow-consistent thickness map and is already implemented in our ice flow model. Information on both ice velocities and ice thickness are a prerequisite to quantify the ice flow divergence that explains a, to this day, largely unknown portion of glacier changes. The reconstruction will therefore make it possible to better interpret recent geometric changes in the light of the observed atmospheric warming in the Arctic. Moreover, previous extrapolations for archipelago-wide estimates of ice volume and discharge can be improved on a physical basis. As the bedrock reconstruction is consistent with the observed ice flow, the map will facilitate the application of ice flow models on Svalbard. With our flow model, we aim at inferring the contribution of basal sliding to present glacier flow.

上个世纪，全球表面温度的上升幅度约为0.7°C。由于对高纬度的慢性变化的遗传放大，在极地区域更加表达变暖。一个显着的后果是上个世纪观察到的斯瓦尔巴德冰川的一般撤退。在过去的几十年中，南部的斯瓦尔巴德冰川甚至以急剧上升的速度向前迈进。但是，在整个北极期间，这种最新的变薄趋势尚未确认。原因依赖于Svalbard的独特气候条件。由于北大西洋的温暖洋流到达了群岛的南端，因此气候对其纬度带的温暖和可变。因此，经常有人建议SVALBARD冰川的进化在其他北极地区起前体的作用。在北极，Svalbard在另一个方面是独一无二的，因为冰川的扩展和高程变化在几十年来都很好地表征了。然而，由于杂志的表面质量平衡和冰流差异，因此抑制了这些几何变化的解释。后来取决于冰川的几何形状和动力学，不一定直接由气候参数的变化控制。然而，对冰川厚度和速度的观察是稀疏且暂时不一致的，这阻碍了今天对Svalbard冰川变化的动态控制的可靠量化。通过扩展，我们只对海洋冰界的冰山产犊每年排放多少数量有一个投票想法。冰排出大概可以解释总质量预算中的很大一部分，因为超过一半的冰覆盖的区域通过海洋终止冰川排水管。为此，从卫星遥感中推断出表面速度，而卫星遥感反过来又可以重建所有冰覆盖区域下的基岩地形。重建利用了质量保护原则，因此提供了一易一度的厚度图，并且已经在我们的冰流模型中实现了。有关冰速度和冰厚度的信息都是量化冰流差异的先决条件，该冰流差异解释了，直到今天，冰川变化的部分很大程度上是未知的部分。因此，重建将使根据北极观察到的大气变暖更好地解释最近的几何变化是可能的。此外，可以在物理的基础上改善群体体积和排放量的以前的冰量和排放估计值的外推。由于基岩的重建与观察到的冰流相一致，因此地图将促进冰流模型在Svalbard上的应用。通过我们的流模型，我们旨在推断基本滑动对呈现冰川流的贡献。

项目成果

A consensus estimate for the ice thickness distribution of all glaciers on Earth

• DOI: 10.1038/s41561-019-0300-3
• 发表时间: 2019-03-01
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Farinotti, Daniel;Huss, Matthias;Pandit, Ankur
• 通讯作者: Pandit, Ankur

The safety band of Antarctic ice shelves

• DOI: 10.1038/nclimate2912
• 发表时间: 2016-05-01
• 期刊: NATURE CLIMATE CHANGE
• 影响因子: 30.7
• 作者: Fuerst, Johannes Jakob;Durand, Gael;Gagliardini, Olivier
• 通讯作者: Gagliardini, Olivier

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

• DOI: 10.5194/tc-11-2003-2017
• 发表时间: 2017-09
• 期刊: The Cryosphere
• 作者: J. Fürst;F. Gillet‐Chaulet;T. Benham;J. Dowdeswell;M. Grabiec;F. Navarro;R. Pettersson;G. Moholdt;C. Nuth;Björn-Lukas Saß;K. Aas;X. Fettweis;C. Lang;T. Seehaus;M. Braun

The Ice‐Free Topography of Svalbard

斯瓦尔巴特群岛的无冰地形

• DOI: 10.1029/2018gl079734
• 发表时间: 2018
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: J.J. Fürst;F. Navarro;F. Gillet-Chaulet;M. Huss;G. Moholdt;X. Fettweis;C. Lang;T. Seehaus;T.J. Benham;D.I. Benn;H. Björnsson;J.A. Dowdeswell;M. Grabiec;J. Kohler;I. Lavrentiev;K. Lindbäck;K. Melvold;R. Pettersson;D. Rippin
• 通讯作者: D. Rippin

How accurate are estimates of glacier ice thickness? Results from ITMIX, the Ice Thickness Models Intercomparison eXperiment

• DOI: 10.5194/tc-11-949-2017
• 发表时间: 2017-04-18
• 期刊: CRYOSPHERE
• 影响因子: 5.2
• 作者: Farinotti, Daniel;Brinkerhoff, Douglas J.;Andreassen, Liss M.
• 通讯作者: Andreassen, Liss M.