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提出的研究将调查北落基山脉气候变化的性质和时间，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年度到世纪尺度的变化来细化早期冰川和花粉研究中描述的气候事件的范围和年代，这些变化以前太细而无法描述。为此，该项目将采用高分辨率、多代理方法，重点关注该地区的两项创新技术：生物诱导碳酸盐的稳定同位素组成和变异沉积物的定年。该研究策略包括将单个湖泊的代理数据与仪器气候记录进行校准，解释和确定过去12000年的短期气候变化的年代，生成详细的时间序列来分析变化的频率，并将一个小湖泊（马尔湖）与一个较大的湖泊（平头湖）进行比较，以评估复杂气候条件下小湖泊记录区域信号的能力。马尔湖的气候解释将主要依赖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。将建立花粉剖面与区域植被研究的相关性。来自较大的平头湖的气候解释将依赖于同位素和湖面的波动。结合沉积物岩心和地震记录将用来推断干旱的时间和持续时间。综合这两个湖泊的有效水分估算和干旱频率将有利于评估主要河流的长期水量，如哥伦比亚河，这是重要的灌溉来源。平头湖地震调查的第二个好处是有机会重建米森谷地区米苏拉冰川湖的历史。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，并可用于测试新一代气候模式的保真度。?？

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. ??