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.

全球地表温度比上个世纪上升了约0.7°C。由于高纬度地区气候变化的固有放大作用，变暖在极地地区表现得更为明显。一个突出的后果是在上个世纪观察到的斯瓦尔巴特群岛冰川的普遍退缩。 在过去的几十年里，斯瓦尔巴特群岛南部的冰川甚至以惊人的速度变薄。然而，这一最新的变薄趋势在整个北极都没有得到证实。原因在于斯瓦尔巴特群岛独特的气候条件。由于北大西洋的温暖洋流到达群岛的南端，气候相当温暖，纬度带多变。斯瓦尔巴特群岛冰川的演变因此经常被认为是其他北极地区的先驱。在北极地区，斯瓦尔巴特群岛在另一个方面是独一无二的，因为冰川的范围和海拔变化在几十年内得到了很好的描述。然而，这些几何变化的气候演变方面的解释是受抑制的，因为它们产生的气候表面质量平衡和冰流的分歧。后者取决于冰川的几何形状和动态，不一定直接受气候参数变化的控制。然而，对冰川厚度和速度的观测是稀疏和时间不一致的，这阻碍了今天对斯瓦尔巴特群岛冰川变化的动态控制的可靠量化。推而广之，我们对每年有多少体积是由海洋冰锋的冰山崩解排出的只有一个模糊的概念。冰流量大概解释了总质量预算的很大一部分，因为超过一半的冰覆盖区通过海洋终止的冰川排水。研究提案的目的是扩大对冰川演变的冰动力学组成部分的知识，以整个斯瓦尔巴群岛。为此，从卫星遥感中推断出表面速度，这反过来又有助于重建所有冰层覆盖地区下面的基岩地形。重建利用质量守恒原理，因此提供了一个流动一致的厚度图，并已在我们的冰流模型中实现。关于冰速度和冰厚度的信息是量化冰流分歧的先决条件，冰流分歧解释了迄今为止在很大程度上未知的冰川变化。因此，重建将使人们能够根据观察到的北极大气变暖情况更好地解释最近的几何变化。此外，可以在物理基础上改进以前对全群岛冰量和流量估计的推断。由于基岩重建与观测到的冰流一致，该地图将有助于斯瓦尔巴特群岛冰流模型的应用。我们的流动模型，我们的目标是推断基底滑动的贡献，目前冰川流量。

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

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

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

Dynamic changes on the Wilkins Ice Shelf during the 2006–2009 retreat derived from satellite observations

根据卫星观测得出的 2006 年至 2009 年撤退期间威尔金斯冰架的动态变化

• DOI: 10.5194/tc-11-1199-2017
• 发表时间: 2009
• 期刊: The Cryosphere
• 作者: M. Rankl;J.J. Fürst ;A. Humbert;M.H. Braun
• 通讯作者: M.H. Braun