Spatial Variability in Firn Properties from Borehole Optical Stratigraphy at the Inland WAIS Core Site

0538639Waddingn该奖项支持一个项目，该项目旨在研究WAIS划分冰芯地点附近的堆积变化模式和微结构特征，该地点位于2.5公里长的20米钻孔阵列中。钻孔光学地层学(BOS)是一种新型的光学测量系统，它探测降雪中由于降雪微结构变化而产生的年度尺度层，给出过去40-50年来积雪如何在空间上变化的年度尺度记录。钻孔光学地层学数据最终可以与FIRN微观结构参数的其他数据进行校准，以校准BOS对密度、孔隙体积和孔隙形状变化的敏感性，并通过代理显示这些参数在整个勘测区的空间变化情况。对层厚和层亮度数据的统计分析将能够预测：1)年际积累变异性，2)由于堆积空间模式的变化而在十年尺度上的层厚变异性，以及3)由于微结构的空间模式变化而导致的微结构驱动变质作用的变异性。有了这些统计数据，测量在WAIS分水岭冰芯中发现的气候变化的科学家将能够确定他们测量的信号由于背景积累变化而超过信号的比例。作为一个额外的好处，当仍然在现场时，我们将通过光学层数来确定积雪的初步深度-年龄标度，直到可用的最深的充气积雪孔的深度。这将是岩心钻探作业和岩心初步数据分析的一个有价值的结果。在更广泛的影响方面，该项目将通过培训博士后现场技术来促进教育。P.I.和博士后研究员将参加一个名为“什么是科学研究？”的本科生研讨会，结合这个项目的进展和成果。他们还将与中学科学和数学课交流他们的进展和实地经验。

0538639WaddingtonThis award supports a project to study the patterns of accumulation variation and microstructural properties near the WAIS Divide ice core site in a 2.5 km array of 20 m boreholes. Borehole Optical Stratigraphy (BOS) is a novel optical measurement system that detects annual-scale layers in firn that result from changes in firn microstructure, giving annual-scale records of how accumulation varied spatially over the last 40-50 years. Data from borehole optical stratigraphy can eventually be calibrated against other data on the microstructural parameters of firn to calibrate BOS's sensitivity to density, pore-volume, and pore-shape variations, and to show by proxy how these parameters vary in space across the survey area. Statistical analysis of layer-thickness and layer-brightness data will enable prediction of: 1) interannual accumulation variability, 2) variability in layer-thickness at decadal scales due to changing spatial patterns in accumulation and 3) variability in microstructure-driven metamorphism due to changing spatial patterns of microstructure. With these statistics in hand, a scientist measuring climatic shifts found in the WAIS Divide ice core will be able to determine the fraction by which signals they measure exceed the signal due to background accumulation variations. As an added benefit, while still in the field, we will determine a preliminary depth-age scale for the firn by optical layer-counting, to the depth of the deepest air-filled firn hole available. This will be a valuable result for core-drilling operations and for preliminary data-analysis on the core. In terms of broader impacts, this project will advance education by training a post-doctoral student in field techniques. The P.I. and the post-doctoral researcher will participate in an undergraduate seminar called "What is Scientific Research?", incorporating progress and results from this project. They will also communicate about their progress and field experience with a middle-school science and math class.