Doctoral Dissertation Research: Proxy Records of Paleohurricane Activities for the Western and Southern Caribbean

该项目旨在建立加勒比地区西部和南部飓风活动的地质替代记录。飓风路径位置的变化发生在各种不同的尺度上，从年际到千年。2004年和2005年飓风对美国造成的破坏极大地表明了这种转变的社会重要性。这一博士论文研究项目的目标是通过将长期气候和飓风历史联系起来，确定导致这些变化的气候强迫机制。到目前为止，由于古飓风记录中的空白，特别是在经常受灾的加勒比地区，这种关联是不可能的。这项研究试图通过从伯利兹、尼加拉瓜和巴巴多斯沿海地区的沉积物岩芯获得代理飓风记录来缩小这一差距。主要飓风(3级或以上)通常通过将可辨认的海滩和海洋物质(如沙子和海洋生物)输送到内陆，并将其沉积在更多有机物质上，在沿海湖泊和沼泽中留下可识别的沉积特征。通过对这些飓风生成的地层进行计数和年代测定，可以确定飓风登陆的全面历史，从几千年到过去。目前的证据表明，在大气环流变化的推动下，墨西哥湾沿岸登陆频率在几个世纪到几千年的时间尺度上发生了戏剧性的变化。这项研究将通过将沉积研究扩展到加勒比海最南端，帮助描绘这些变化的时间和空间范围。过去的气候条件将通过对岩心进行的花粉分析和公布的记录来确定，而实验室对磁化率、电阻率、有机含量和颗粒大小的分析将用于识别飓风生成的地层。时间控制将通过放射性碳测年进行。将代理飓风记录扩展到未经研究的加勒比海地区将有助于更清楚地了解区域内的长期飓风行为，而将飓风和气候记录联系起来将有助于我们更好地理解两者之间的关系。将飓风活动作为更大环流模式的一个互动组成部分进行调查，有助于解开复杂的联系。自1990年代中期以来，飓风路径的频率和位置的改变在加勒比和美国造成了巨大的财产损失和生命损失，因此，进一步了解控制登陆地点和频率的机制将具有重大的社会价值。澄清飓风在北大西洋气候系统中的作用以及这些关系如何应对不断变化的气候条件，是制定有效的社会对策应对这一严重自然灾害的关键一步。

This project aims to establish the geological proxy records of hurricane activities in the western and southern parts of the Caribbean region. Shifts in the location of hurricane tracks occur across a variety of scales, from interannual to millennial. The damage hurricanes inflicted upon the United States during the 2004 and 2005 seasons dramatically demonstrates the societal importance of such shifts. The goal of this doctoral dissertation research project is to identify the climatic forcing mechanisms responsible for these shifts by correlating long-term climate and hurricane histories. Such a correlation has not heretofore been possible due to gaps in the paleohurricane record, particularly from the oft-struck Caribbean region. This study attempts to close this gap by obtaining proxy hurricane records from sediment cores from coastal sites in Belize, Nicaragua and Barbados. Major hurricanes (category 3 or greater) typically leave an identifiable sedimentary signature in coastal lakes and swamps by transporting recognizable beach and marine material, such as sand and marine organisms, inland where it is deposited onto more organic material. A comprehensive history of hurricane landfalls extending thousands of years into the past can be determined by counting and dating these hurricane-generated layers. Present evidence indicates dramatic changes in landfall frequency for the Gulf Coast on timescales of centuries to millennia, driven by changes in atmospheric circulation. This study will help delineate the temporal and spatial extent of these changes by extending sedimentary studies to the far southern Caribbean. Past climate conditions will be ascertained from a pollen analysis conducted on the cores and from published records, while laboratory analyses of magnetic susceptibility, electric resistivity, organic content, and grain size will be used to identify hurricane-generated layers. Chronological control will be by radiocarbon dating. Extending the proxy hurricane record to unstudied Caribbean areas will facilitate a clearer understanding of long-term hurricane behavior on a regional basis, while connecting the hurricane and climatic records will improve our understanding of the relationship between the two. Investigating hurricane activity as an interactive component of the larger circulation patterns facilitates untangling the complex connections. Since property damage and loss of life in the Caribbean and the United States resulting from the shift in the frequency and location of hurricane paths since the mid 1990s has been tremendous, any increased understanding of the mechanisms controlling the location and frequency of landfall will be of great societal value. The clarification of the role hurricanes play in the North Atlantic climate system and the way these relationships respond to changing climatic conditions is a critical step towards developing an effective societal response to this serious natural hazard.