Reconstructing the Past 1000 Years of Climate Variability in Equatorial East Africa with Decade-Scale Resolution, from the Sediment Record of a Submerged Crater Basin (ESH)

9631364 H.Wright拟议的研究将调查落基山脉北部气候转变的性质和时间，同时评估山区小湖泊记录区域气候的可靠性。这项研究的目的是通过确定以前无法描述的年度到百年尺度的变化，来完善早期冰川和花粉研究中所描述的气候事件的范围和年表。为此，该项目将使用高分辨率、多代理方法，重点是该地区的两项创新技术：生物成因碳酸盐的稳定同位素组成和不同沉积物的测年。研究战略包括校准从单个湖泊到仪器气候记录的替代数据，解释和测定过去12,000年的短期气候变化，产生详细的时间序列来分析变化的频率，并将小湖泊(Marl Lake)与较大的湖泊(Flathead)进行比较，以评估处于复杂气候状况的小湖泊记录区域信号的能力。泥灰湖的气候解释将主要依赖于自生碳酸盐的稳定同位素组成、与盐度变化相关的硅藻组合的变化、沉积物特征和介形类的微量元素。将建立与区域植被研究相关的花粉分布图。来自更大的平头湖的气候解释将依赖于同位素和湖平面的波动。结合沉积物-岩心和地震记录将被用来推断干旱的时间和持续时间。综合两个湖泊的有效湿度估计和干旱频率，将有助于评估主要河流的长期产水量，如哥伦比亚河，这些河流是灌溉的关键来源。对平头湖进行地震调查的第二个好处是有机会重建米苏拉湖在米西翁河谷地区的历史。这些结果将为从小流域收集的数据的区域准确性提供指导方针，并可用于测试新一代气候模型的保真度。?？

9631364 H. Wright The proposed research will investigate the nature and timing of climatic transitions in the Northern Rocky Mountains while assessing the reliability of small lakes in mountainous regions to record regional climate. The study is aimed at refining the scope and chronology of climatic events described in earlier glacial and pollen studies by identifying annual to century-scale variations that were previously too fine to be described. To do so, the project will use a high-resolution, multi-proxy approach, with emphasis on two innovative techniques for the region: stable-isotopic composition of bio-induced carbonates and dating with varved sediment. The research strategy includes calibrating proxy data from single varves to the instrumental climate record, interpreting and dating short-term climatic variations for the last 12,000 years, producing a detailed time series to analyze frequencies of change, and comparing a small varved site (Marl Lake) with a larger lake (Flathead) to assess the ability of small lakes in complex climatic regimes to record a regional signal. Climatic interpretations from Marl Lake will rely principally on the stable-isotopic composition of authigenic carbonates, changes in diatom assemblages associated with salinity changes, sediment characteristics, and trace-elements of ostracodes. A pollen profile will be constructed for correlation with regional vegetation studies. Climatic interpretations from the larger Flathead Lake will rely on isotopic- and lake-level fluctuations. The combined sediment-core and seismic records will be used to infer the timing and duration of drought. Synthesis of effective-moisture estimates and drought frequency for the two lakes will be beneficial in the assessment of long-term water yield of major rivers, such as the Columbia, which are critical sources of irrigation. A secondary benefit from the seismic survey of Flathead Lake is the opportunity to reconstruct the history of Glacial Lake Missoula in the Mi ssion Valley region. The results will provide guidelines regarding the regional accuracy of data collected from small basins and can be used to test the fidelity of a new generation of climate models. ??