Collaborative Research: Early-Versus Late- Holocene Drought Variations in the Northern Rocky Mountains

合作研究：落基山脉北部早全新世与晚全新世的干旱变化

• 批准号: 9906100
• 负责人: Cathy Whitlock
• 金额: $ 14.39万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9906100&HistoricalAwards=false
• 关键词: Collaborative; Research; Early; Versus; Late; Collaborative; Research; Early; Versus; Late

This study proposes to investigate high-frequency drought events in northwestern Montana for two time intervals: 0-2000 and 7000-9000 14C yr BP. The principal goals are to reconstruct the timing, severity, and cyclicities of shifts in effective moisture so that we may address the following questions: 1) Are drought frequencies correlative in time with known solar and/or oceanic-atmospheric frequencies? 2) Does the frequency of drought change over the last 10 ka BP and are these changes correlative with changes in the climatic boundary conditions? 3) Does the timing of drought in the Northwest have a defined relationship to that of adjacent regions?Three climatic proxies preserved in lake sediments-- the d18O of carbonates, diatom assemblages, and charcoal-will be used to answer these questions. The combined use of d18O and diatoms potentially provides an innovative technique for estimating the severity, as well as the seasonal timing of drought. The addition of charcoal analyses permits the study the effects of drought on both aquatic and terrestrial ecosystems. The study aims to reconstruct high-frequency climatic variations at decadal to sub-decadal resolution. The records will be dated with a combination of varve counts and multiple 14C dates to ensure as accurate and detailed a chronology as possible. Three sites were chosen for analysis to mediate potential complications caused by local climatic effects in mountainous regions.

这项研究提议研究蒙大拿州西北部的高频干旱事件两个时间间隔：0-2000和7000-9000 14C年BP。 主要目标是重建有效水分转移的时机，严重性和周期性，以便我们可以解决以下问题：1）与已知的太阳能和/或大气频率的及时相关的干旱频率是相关的吗？ 2）干旱的频率是否在最后10 ka bp中发生变化，这些变化是否与气候边界条件的变化相关？ 3）西北干旱的时机是否与邻近地区的干旱有明确的关系？三个保存在湖沉积物中的气候代理 - 碳酸盐，硅藻组合和木炭 - 将使用来回答这些问题。 D18O和硅藻的联合使用可能提供了一种创新的技术，用于估计严重程度以及干旱的季节性时机。 木炭分析的添加允许研究干旱对水生生态系统的影响。 该研究旨在重建在deCADAL deCADAL中的高频气候变化。 记录将结合使用量值和多个14C日期，以确保尽可能准确和详细的年表。 选择三个地点进行分析，以介导山区局部气候影响引起的潜在并发症。