Modelling Glacier and Ice Sheet Response to Climate Change

模拟冰川和冰盖对气候变化的响应

基本信息

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：
2020
资助国家：
加拿大
起止时间：
2020-01-01 至 2021-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713207
关键词：
Modelling Glacier Ice Sheet Response

项目摘要

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及其在冰川学和气候模型中的表示的了解。现场地点包括加拿大西部和北极地区、冰岛和格陵兰岛，我的建模工作涵盖了一系列空间和时间尺度，从山地冰川对气候变化的响应到冰河时代冰盖的演变和气候动态。本次发现资助周期的拟议研究包含每一个不同的研究线索，但将重点关注加拿大西部山区冰原和格陵兰冰盖（那里的冰雪位于季节性降雪之下）积聚区域的融水排水、重新冻结和保留。冰雪含水层中的融水再冻结和液态水储存可实现内部积累，保留系统内的质量并减少冰川径流。尽管越来越多的证据表明需要了解冰川过程以准确模拟冰川质量平衡、融水径流和海平面上升，但这一过程通常不会出现在冰川和冰盖对气候变化响应的模型中。此外，融水滞留和再冻结会影响冰雪密度，需要了解冰雪密度来解释用于监测冰川和冰盖变化的机载和卫星测高数据。拟议的研究目标是融水滞留的热力学和水文控制及其对冰川热状况、致密化、冰川质量平衡、融水径流和同位素地层学的影响。实地研究将在格陵兰岛南部的 Dye2、育空地区圣埃利亚斯山脉的 Kaskawulsh 冰川上部以及加拿大西部的哥伦比亚和伊勒西勒瓦特冰原进行。每个地点预计有一到两个野外季节，以获取浅冰芯（深度达 50 m），并研究在季节性雪和冰雪中挖掘的近地表坑（深度达 5 m）中融水的渗透和再冻结。这些坑将配备热敏电阻和时域反射计（TDR）探头，以跟踪雪/雪松液态水含量以及融水重新冻结时释放潜热的热信号。冰芯将提供融水渗透和冰层内容的更深入的表示。人们对加拿大西部和北部的冷杉的深度和特性知之甚少。这些研究将为冰雪表征提供主要数据，这将指导用于大规模冰原和冰盖建模的冰雪模型的开发。除了冰水文学和热力学之外，还将分析稳定同位素（d18O、dD），以了解融水渗透和再冻结对稳定同位素地层学和测温的影响，以支持基于冰芯的气候重建。