Modelling Glacier and Ice Sheet Response to Climate Change

我的研究小组将实地研究和数值模拟相结合，研究冰川动力学和冰川-气候过程。我的主要目的是增进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表现。现场地点包括加拿大西部和北极、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，从山脉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。*关于这个探索基金周期的拟议研究包含这些不同的研究线索，但将专注于加拿大西部山区冰场和格陵兰冰盖积累区的融水排水、重新冻结和保留，那里的积雪是季节性积雪的基础。融水重新冻结和积雪含水层中的液态水储存产生了内部积累，将质量保留在系统内，减少了冰川径流。这一过程在冰川和冰盖对气候变化的响应模型中通常没有表现出来，尽管越来越多的证据表明，为了准确地模拟冰川质量平衡、融水径流和海平面上升，需要了解降雪过程。此外，融水滞留和重新冻结影响降雪密度，需要知道该密度才能解释用于监测冰川和冰盖变化的航空和卫星测高数据。这项拟议的研究旨在研究融水滞留的热力学和水文学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。*将在格陵兰岛南部的Dye2，圣埃利亚斯山脉的上Kaskawulsh冰川，育空地区，以及加拿大西部的哥伦比亚和Illecillewaet冰原进行实地研究。预计每个地点将有一到两个野外季节，以获取浅冰芯(深达50米)，并研究在季节性积雪和积雪中挖掘的近地表坑(深达5米)中的融水渗透和再冻结。这些深坑将配备热敏电阻和时域反射仪(TDR)探头，以跟踪积雪/降雪的液态水含量和融水重新结冰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表示。人们对加拿大西部和北部降雪的深度和性质知之甚少。这些研究将为降雪特征描述提供原始数据，这将指导大范围冰场和冰盖模拟的降雪模式的发展。除了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。

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.**