Collaborative Research: Trapped Gas Composition and the Chronology of the Vostok Ice Core

高纬度深冰芯包含极地温度、大气尘埃负荷（和大陆干旱）、温室气体浓度、生物圈状况和过去环境的其他基本特性的基本记录。如果要充分认识到这些记录的重要性，就需要一个准确的年表。测年的挑战刺激了轨道调整的努力。在这种方法中，人们在允许的范围内改变一个时间尺度，以优化古环境属性与随时间变化的日照曲线之间的匹配。由于直接的日晒强迫，理想的性能会随时间而变化。它将不受复杂的气候反馈和遥相关的影响，它将给出一个高信噪比的干净记录。有人强烈认为，冰芯捕获气体的O2/N2比率就是这样一种性质，并且有证据表明，这种性质与当地夏季日照有关，其大气比率几乎是恒定的。该合同将支持Vostok冰芯中~ 115-400 ka间隔1kyr的O2/N2比值分析项目。辅助测量Ar/N2、Ne/N2和重惰性气体比，以了解气泡封闭分馏及其在Vostok圈闭气记录中的表现。O2/N2变化将与Vostok的夏季日照相匹配，以实现Vostok核心的高精度年表。沃斯托克和其他相关的气候记录将被重新检查，以提高我们对更新世气候变化动力学的理解。

High latitude deep ice cores contain fundamental records of polar temperatures, atmospheric dust loads (and continental aridity), greenhouse gas concentrations, the status of the biosphere, and other essential properties of past environments. An accurate chronology for these records is needed if their significance is to be fully realized. The dating challenge has stimulated efforts at orbital tuning. In this approach, one varies a timescale, within allowable limits, to optimize the match between a paleoenvironmental property and a curve of insolation through time. The ideal property would vary with time due to direct insolation forcing. It would be unaffected by complex climate feedbacks and teleconnections, and it would give a clean record with high signal/noise ratio. It is argued strongly that the O2/N2 ratio of ice core trapped gases is such a property, and evidence is presented that this property, whose atmospheric ratio is nearly constant, is tied to local summertime insolation. This award will support a project to analyze the O2/N2 ratios at 1 kyr intervals from ~ 115-400 ka in the Vostok ice core. Ancillary measurements will be made of Ar/N2, and Ne/N2 and heavy noble gas ratios, in order to understand bubble close-off fractionation and its manifestation in the Vostok trapped gas record. O2/N2 variations will be matched with summertime insolation at Vostok to achieve a high-accuracy chronology for the Vostok core. The Vostok and other correlatable climate records will then be reexamined to improve our understanding of the dynamics of Pleistocene climate change.