The Physical Properties of the US ITASE Ice Cores

9980434 Meese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。 第一优先事项将是检查目视地层学，以描绘年度层结构，用于测年目的，并确定尽可能大的深度，在地层测年岩心的全长上的累积变化。 第二个目标是测量和分析深度-密度分布。 雪和雪的致密化速度取决于雪沉积的速度和雪的原位温度。 这些数据可以并将被用来获得平均积雪率的网站，年度层结构是难以破译或地层分析完全失败。 第三个目标是测量整个岩芯的平均晶体尺寸。 晶体生长是一个与温度密切相关的过程，在ITASE核心上进行的测量将有助于弥补年平均温度范围（-31至-50摄氏度）存在的重大数据缺口。 此外，晶体尺寸数据也可以与基于密度剖面测量的冰负荷结合使用，以提取这些地点的平均累积速率，其中岩心的地层年代测定证明是困难或不可能完成的。 这可能发生在ITASE穿越路线沿着的最低累积/最低温度站点。

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.