Collaborative Research: Firn structure, interstitial processes and the composition of firn air at Summit, Greenland

合作研究：格陵兰萨米特的冷杉结构、间隙过程和冷杉空气的成分

• 批准号: 0520564
• 负责人: Jeffrey Severinghaus
• 金额: --
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0520564&HistoricalAwards=false
• 关键词: Collaborative; Research; Firn; structure; interstitial

ABSTRACTAlbertOPP-0520445SeveringhausOPP-0520564BattleOPP-0520460Intellectual merit: An important issue of our time involves questions of how human activity has been impacted by the atmospheric composition of our planet. A major area as part of the International Polar Year (IPY) involves developing a better understanding of past climates and the impact of anthropogenic activity on the Earth's atmosphere. Because instrumental records of atmospheric chemistry are limited, natural archives of atmospheric composition must be made, such as polar firn. Its porous nature, tens of meters in depth, permits interstitial diffusion of gases over time with the oldest air at the bottom of the firn column which allows the sampling of large quantities of pre-industrial air to explore anthropogenic effects on the atmosphere. This project will investigate the underlying physics controlling firn's ability to store atmospheric samples from the past. The Principal Investigators will make high-resolution measurements of the diffusivity profile, permeability profile, and accompanying microstructure at Summit from the surface to pore close-off, and compare the results to the diffusivity profile inferred from measurements of firn air chemical composition. They will partner with Dr. Atsumu Ohmura, Swiss Federal Institute, and Dr. Christophe Ferrari of LGGE, France. This project has four goals: 1) Quantify the dependence of interstitial transport processes on firn microstructure, and determine the dependence of gas diffusivity on microstructure characteristics from the surface down to the pore close-off depth; 2) Quantify post-depositional changes in the physical properties of snow and firn and use measured properties of firn and meteorological data to evaluate and develop models of the physical transport processes which drive firnification where temperature gradients are large. 3) Conduct firn air chemical measurements as the firn characteristics are determined, and compare the co-registered diffusivity profile inferred from the firn air chemistry measurements to the high-resolution tracer gas measurements made on the firn core itself. 4) Use the measurements of firn air composition and firn structure to better quantify the differences between atmospheric composition (present and past), and the air trapped in both the firn, and in air bubbles within ice. Broader Impacts: This study will establish quantitative relationships that will enable a better understanding of the firn as a repository of past atmospheric composition, but will also enable us to understand mechanisms that may impact firn air composition at other sites. Results of the research will be published in journal articles and made widely available. This project will form one part of the PhD dissertation of a student from Dartmouth. Several undergraduates will be involved. They will interact with students from Switzerland and France to design and construct an IPY museum exhibit, at the Montshire Museum of Science in Norwich, Vermont. The exhibit will be interactive and will illustrate the ability of snow and firn to serve as an archive of important events of the past. It will allow the viewer to act as the "detective" to track down the meaning of different chemical composition profiles in the firn air.

摘要AlbertOPP-0520445SeveringhausOPP-05205​​64BattleOPP-0520460智力价值：我们这个时代的一个重要问题涉及人类活动如何受到地球大气成分影响的问题。 作为国际极地年（IPY）一部分的一个主要领域涉及更好地了解过去的气候以及人类活动对地球大气的影响。由于大气化学的仪器记录有限，必须建立大气成分的自然档案，例如极地雪。它的多孔性质，深度达数十米，允许气体随着时间的推移与冷杉柱底部最古老的空气进行间隙扩散，从而可以对大量工业化前的空气进行采样，以探索人为对大气的影响。该项目将研究控制firn存储过去大气样本的能力的基本物理原理。主要研究人员将对 Summit 从表面到孔隙封闭的扩散率剖面、渗透率剖面和伴随的微观结构进行高分辨率测量，并将结果与​​通过测量空气化学成分推断出的扩散率剖面进行比较。他们将与瑞士联邦研究所的 Atsumu Ohmura 博士和法国 LGGE 的 Christophe Ferrari 博士合作。 该项目有四个目标：1）量化间隙传输过程对微结构的依赖性，并确定气体扩散率对从表面到孔隙封闭深度的微结构特征的依赖性； 2）量化雪和冷杉物理特性的沉积后变化，并使用测量的冷杉特性和气象数据来评估和开发在温度梯度较大的情况下驱动冷杉化的物理传输过程模型。 3) 在确定了云杉特性后进行云杉空气化学测量，并将从云杉空气化学测量推断出的共同记录的扩散率剖面与在云杉核心本身上进行的高分辨率示踪气体测量进行比较。 4) 使用冰块空气成分和冰块结构的测量来更好地量化大气成分（现在和过去）以及冰块中和冰内气泡中捕获的空气之间的差异。更广泛的影响：这项研究将建立定量关系，使我们能够更好地了解雪恩作为过去大气成分的储存库，同时也使我们能够了解可能影响其他地点雪恩空气成分的机制。研究结果将发表在期刊文章中并广泛传播。该项目将构成达特茅斯学生博士论文的一部分。几位本科生将参与其中。 他们将与来自瑞士和法国的学生互动，在佛蒙特州诺里奇的蒙特郡科学博物馆设计和建造一个 IPY 博物馆展览。该展览将是互动的，并将展示雪和冷杉作为过去重要事件档案的能力。它将允许观看者充当“侦探”来追踪空气中不同化学成分分布的含义。