Modelling Glacier and Ice Sheet Response to Climate Change

模拟冰川和冰盖对气候变化的响应

• 批准号: RGPIN-2018-04763
• 负责人: Marshall, Shawn
• 金额: $ 4.44万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=691053
• 关键词: Modelling; Glacier; Ice; Sheet; Response

My research group combines field studies and numerical modelling to study glacier dynamics and glacier-climate processes. My main aim is to improve the understanding of glaciers and ice sheets in the climate system and their representation in glaciological and climate models. Field sites include western and Arctic Canada, Iceland, and Greenland, and my modelling work is across a range of spatial and temporal scales, from mountain glacier response to climate change to the evolution of Ice Age ice sheets and climate dynamics. *** *The proposed research over this Discovery Grant cycle contains each of these different research threads, but will focus on meltwater drainage, refreezing, and retention in the accumulation area of mountain icefields in western Canada and the Greenland Ice Sheet, where firn underlies the seasonal snow. Meltwater refreezing and liquid water storage in firn aquifers give internal accumulation, retaining mass within the system and reducing glacier runoff. This process is generally not represented in models of glacier and ice sheet response to climate change, despite growing evidence that firn processes need to be understood for accurate modelling of glacier mass balance, meltwater runoff, and sea level rise. Moreover, meltwater retention and refreezing impact firn density, which needs to be known to interpret airborne and satellite altimetry data that are used to monitor glacier and ice sheet change. The proposed research targets the thermodynamic and hydrological controls of meltwater retention and its implications for glacier thermal regime, densification, glacier mass balance, meltwater runoff, and isotope stratigraphy. *** *Field studies will be conducted at Dye2 in southern Greenland, the upper Kaskawulsh Glacier in the St. Elias Mountains, Yukon, and the Columbia and Illecillewaet Icefields in western Canada. One to two field seasons are anticipated at each site, to acquire shallow ice cores (up to 50 m depth) and study meltwater percolation and refreezing in the near-surface pits (up to 5 m depth) excavated in the seasonal snow and firn. The pits will be instrumented with thermistors and time-domain reflectometry (TDR) probes, to track snow/firn liquid water content and the thermal signal of latent heat release as meltwater refreezes. The ice cores will provide a deeper representation of meltwater percolation and ice layer content. Little is known about the depth and properties of firn in western and northern Canada. These studies will offer primary data into firn characterization, which will guide the development of a firn model for large-scale icefield and ice sheet modelling. In addition to the firn hydrology and thermodynamics, stable isotopes (d18O, dD) will be analyzed to understand the impacts of meltwater percolation and refreezing on stable isotope stratigraphy and thermometry, in support of ice-core based climate reconstructions.**

我的研究小组结合实地研究和数值模拟来研究冰川动力学和冰川气候过程。我的主要目标是提高对气候系统中冰川和冰盖的理解，以及它们在冰川学和气候模型中的代表性。实地考察地点包括加拿大西部和北极地区，冰岛和格陵兰岛，我的建模工作跨越了一系列的空间和时间尺度，从山地冰川对气候变化的反应到冰河时代冰盖和气候动态的演变。*** * 本发现资助周期的拟议研究包含这些不同的研究线索，但将侧重于加拿大西部山区冰原和格陵兰冰盖积累区的融水排水，再冻结和保留，其中积雪是季节性雪的基础。融水再冻结和液态水储存在积雪含水层中，形成内部积累，将质量保留在系统内，减少冰川径流。这一过程一般不代表冰川和冰盖对气候变化的反应模型，尽管越来越多的证据表明，积雪过程需要了解冰川质量平衡，融水径流和海平面上升的准确建模。此外，融水滞留和再冻结影响积雪密度，这需要知道解释用于监测冰川和冰盖变化的航空和卫星测高数据。拟议的研究目标的热力学和水文控制融水保留及其对冰川热制度，致密化，冰川质量平衡，融水径流，同位素地层学的影响。*** * 实地研究将在格陵兰南部的Dye 2、育空地区圣埃利亚斯山脉的Kaskawulsh冰川上游以及加拿大西部的哥伦比亚和Ijuillewaet冰原进行。预计在每个地点进行一至两个实地考察季节，以获取浅冰芯（深度达50米），并研究在季节性积雪和积雪中挖掘的近地表坑（深度达5米）中的融水渗透和再冻结情况。这些坑将装有热敏电阻和时域反射仪（TDR）探头，以跟踪雪/积雪液态水含量和融水重新冻结时潜热释放的热信号。冰芯将提供融水渗透和冰层含量的更深层次的代表性。对加拿大西部和北方的积雪深度和性质知之甚少。这些研究将提供有关积雪特征的主要数据，从而指导为大规模冰原和冰盖建模开发一个积雪模型。除了雪层水文学和热力学，还将分析稳定同位素（d18 O，dD），以了解融水渗透和再冻结对稳定同位素地层学和温度测量的影响，以支持基于冰芯的气候重建。