Model Studies of Surface Meltwater Lakes of the Greenland Ice Sheet

该奖项是根据2009年《美国复苏和再投资法》(公法111-5)资助的。提供MacAyeal 0907834芝加哥大学基金会的目的是为了更好地了解格陵兰冰盖表面融水生产的过程和后果，特别是表面湖泊的发展及其随后向冰下床排水的过程，并借助旨在模拟格陵兰冰盖上融水湖泊演变的数值模型。这项工作的重点将是：(A)建立一个自洽的热力学处理方法，利用地表能量平衡模型明确处理辐射强迫问题；(B)研究导致湖泊排入冰下河床的输水管道的动力学问题的新方法。地表能量平衡公式将具体说明太阳、云和晴空在所有重要波长波段(如短波和长波)的向下辐射，使用整体传输公式对敏感和潜热通量进行参数化，并明确地模拟地表以下的热传递过程。提出的输水管道动力学的新方法将涉及随机过程，该随机过程涉及预先存在的裂隙系统的激活，假设裂隙系统具有概率密度函数描述的空间密度和取向。模式开发和试验将产生两个成果：(1)一系列数值模拟，旨在解决有关格陵兰冰盖表面湖泊的形成及其向冰盖床排水的基本问题；(2)发展不同模式方法的框架，并将其应用于大尺度冰盖模式的次网格尺度参数化，从而将它们与气候模式结合起来。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).MacAyeal 0907834University of ChicagoFunds are provided to develop a better understanding of the processes and consequences of surface meltwater production on the Greenland ice sheet, particularly the development of surface lakes and their subsequent drainage to the subglacial bed, with the aid of numerical models designed to simulate the evolution of meltwater lakes on the Greenland Ice Sheet. The work effort will focus on: (a) establishing a self-consistent thermodynamic treatment that explicitly treats radiative forcing using a surface energy balance model, and (b) investigating new approaches to the dynamics of englacial water conduits that cause lake drainage to the subglacial bed. The surface energy balance formulation will specify the downward radiation from sun, clouds and clear sky in all the important wavelength bands (e.g., shortwave and longwave), use bulk transfer formulations to parameterize sensibleand latent-heat fluxes, and explicitly model heat transfer processes below the surface. The new approaches to englacial water conduit dynamics proposed will involve stochastic processes involved in activation of pre-existing crack systems assumed to have spatial density and orientations described by probability density functions. Two products will result from the model development and experimentation: (i) a series of numerical simulations designed to address basic questions concerning the formation of surface lakes on the Greenland Ice Sheet and their drainage to the ice-sheet bed and (ii) the development of a framework of diverse model approaches and their application to the sub-grid-scale parameterization of large-scale ice-sheet models, thereby coupling them to climate models.