High-Resolution Climatic Variability in the Southwestern U.S. During the Last Millennium

摘要：美国南加州德隆大学ATM-9615875 Ku该奖项支持一项研究项目，该项目旨在开发一种有效的代理工具，使pi能够在过去一千年的次年代际（3-10年）时间尺度上重建美国西南部的降水变化。这是一个与厄尔尼诺/南方涛动（ENSO）事件相关的大气远相关的地区（至少是南部）。关键的方法是采用高分辨率氧同位素测量从俄勒冈州、加利福尼亚州和内华达州沿N-S样带的封闭盆地湖泊中提取的年代碳酸盐沉积物。该方法的基础是，通过降雨和径流进入闭合型湖泊的水主要是通过蒸发离开，湖泊的同位素组成反映了水文平衡，可以监测特定时间区域气候变化，特别是降水变率。湖泊沉积物的自生碳酸盐矿物记录了过去湖泊水同位素组成的变化。最近在莫诺湖进行的一项研究已经测试了拟议研究的可行性。该方法将允许pi评估湿气来源（来自三种气候制度：太平洋、大陆和墨西哥湾）及其相对强度，并检测风暴路径在时域上的任何变化。预计该研究将使pi能够评估小冰期、中世纪暖期和ENSO等气候异常，并有助于了解次年代际气候变率的原因和动态。

Abstract ATM-9615875 Ku, Teh-Lung University of Southern California Title: High-Resolution Climatic Variability in the Southwestern U.S. During the Last Millennium This award supports a research project aimed at developing an effective proxy tool which will enable the PIs to reconstruct the precipitation variability on sub-decadal (3-10 years) time scales for the past millennium in the southwestern U.S. This is a region (at least the southern part) of atmospheric teleconnection associated with the El Nino/Southern Oscillation (ENSO) events. The key approach is to employ the high-resolution oxygen isotopic measurement on dated carbonate sediments retrieved from closed- basin lakes located along a N-S transect in Oregon, California and Nevada. The basis for the approach lies in the fact that water entering a closed-basin lake via rain and runoff mostly leaves by evaporation, and the lake's isotopic composition reflects the hydrologic balance that serves to monitor the regional climate change, especially the precipitation variability, at a given time. Past variations of lake water isotopic composition are recorded by authigenic carbonate minerals of the lacustrine sediment. The feasibility of the proposed research has been tested in a recent study conducted in Mono Lake. The method will allow the PIs to assess the moisture sources (from three climatic regimes: Pacific, continental, and Gulf of Mexico) and their relative strengths and detect any shifts in storm track in the time domain. It is anticipated that the study will allow the PIs to evaluate such climatic anomalies as the Little Ice Age, Medieval Warm Period, and ENSO, and contribute to the understanding of the causes and dynamics of sub-decadal climatic variability.