The Physical Properties of the US ITASE Ice Cores

该奖项是为了支持一个项目，该项目旨在研究美国ITASE冰芯的视觉地层学、物理和结构特性，这些冰芯跨越了南极洲过去200年的积雪。首要任务将是检查目视地层学，为定年目的划定年度层结构，并在地层定年的岩心的整个长度上确定尽可能大的深度和堆积变异性。第二个目标是测量和分析深度-密度剖面。雪和雪的密度取决于雪的沉积速率和原地雪温。这些数据可以并将用于计算年层结构难以破译或地层分析完全失败的地点的平均积雪率。第三个目标将需要测量整个岩心长度的平均晶体尺寸。晶体生长是一个高度依赖温度的过程，在ITASE核心上进行的测量将有助于弥合在-31至-50摄氏度的年平均温度范围内存在的重大数据差距。此外，晶体尺寸数据也可以与基于密度剖面测量的冰负荷相结合，用于提取岩心地层测年困难或不可能完成的地点的平均堆积率。这很可能发生在ITASE穿越路线上最低积累/最低温度的地点。

9980434MeeseThis award is for support for a project to examine the visual stratigraphy, physical and structural properties of the U.S. ITASE ice cores spanning the last 200 years of snow accumulation in Antarctica. A first priority will be to examine visual stratigraphy to delineate annual layer structure for dating purposes and to determine to as great a depth as possible, accumulation variability over the full length of a stratigraphically dated core. A second objective is to measure and analyze depth-density profiles. The rate of snow and firn densification depends on both the rate at which the snow is deposited and the in situ snow temperature. These data can and will be used to derive average snow accumulation rates for the sites where annual layer structure is difficult to decipher or where stratigraphic analysis fails altogether. A third objective will entail measurements of mean crystal size over the full length of a core. Crystal growth is a strongly temperature dependent process and measurements to be made on ITASE cores will help to bridge a significant data gap that exists in the mean annual temperature range, -31 to -50 degrees centigrade. Additionally, crystal size data can also be used, in conjunction with ice loads based on density profile measurements, to extract mean accumulation rates for these sites where stratigraphic dating of cores proves difficult or impossible to accomplish. This is likely to occur at the lowest accumulation/lowest temperature sites along the ITASE traverse routes.