Firn Properties and Processes at Shallow Coring Sites in Greenland

拟议的项目将研究影响空气中的热量、蒸汽和化学物质融入雪和极地积雪的方式的物理过程。 这些过程包括扩散和平流，热量、蒸汽和化学物质通过雪和积雪中的气流的输送。 对这些过程的理解是重要的，因为它们控制着颗粒生长、雪的变质以及大气中的化学物质融入雪和积雪的速率，因此将影响对极地冰芯数据的解释。 该项目的目标是确定这些转移过程在空间和时间上的幅度和范围，并发展对雪和积雪现象的过程级理解和建模能力。 该方法是在格陵兰冰盖上获得浅层岩心和气象数据的地点进行实地研究，以确定关键参数的空间和时间范围，以及模拟积雪内热量、质量和化学物质的传导和平流所需的边界条件。 目前正在扩大一个现有的多维数值模型，以模拟这些过程，并作为目前和今后在化学物种的运输和分布方面开展工作的基础。 目前对极地冰芯数据的解释假设扩散控制着化学物质进入积雪的速率。 拟议的项目将确定特定地点的通风程度，在积雪，并将提供一个模型的多维扩散和通风的谷物生长，升华率，和化学物质的运输。

The proposed project examines physical processes that affect the manner in which heat, vapor, and chemical species in air are incorporated into snow and polar firn. The processes include diffusion and advection, the transport of heat, vapor, and chemical species by air flow within snow and firn. An understanding of these processes is important because they control grain growth, snow metamorphism, and the rate at which chemical species in the atmosphere become incorporated into the snow and firn, and thus will affect interpretation of polar ice core data. The objectives of the project are to define the magnitude and extent, both in space and time, of these transfer processes, and to develop a process-level understanding and modeling capability of the phenomena within the snow and firn. The approach is to conduct field studies at sites where shallow cores and meteorological data are being obtained on the Greenland Ice Sheet to determine the spatial and temporal extent fro key parameters, and boundary conditions needed to model the conduction and advection of heat, mass and chemical species within the firn. An existing multidimensional numerical model is being expanded to simulate the processes and serve as the basis for ongoing and future work in transport and distribution of chemical species. Currently interpretation of the polar ice core data assumes that diffusion controls the rate at which chemical species are incorporated into the firn. The proposed project will determine the site-specific extent of ventilation in the firn, and will provide a model for multidimensional diffusion and ventilation on grain growth, sublimation rates, and chemical species transport.