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

该项目旨在建立加勒比区域西部和南部飓风活动的地质代用记录。飓风路径位置的变化发生在不同的尺度上，从年际到千年。2004年和2005年飓风季节对美国造成的破坏戏剧性地表明了这种转变的社会重要性。这个博士论文研究项目的目标是通过将长期气候和飓风历史相关联来确定造成这些变化的气候强迫机制。由于古飓风记录的空白，特别是来自经常遭受袭击的加勒比地区的记录，这种相关性迄今为止还不可能。本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心中获得替代飓风记录来缩小这一差距。大型飓风（3级或以上）通常会在沿海湖泊和沼泽中留下可识别的沉积物特征，将可识别的海滩和海洋物质（如沙子和海洋生物）输送到内陆，沉积在更多的有机物质上。通过计算和确定这些飓风产生的地层的年代，可以确定飓风登陆的数千年的历史。目前的证据表明，在大气环流变化的驱动下，墨西哥湾沿岸的登陆频率在数百年至数千年的时间尺度上发生了巨大变化。这项研究将有助于通过将沉积研究扩展到遥远的加勒比南部来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芯进行的花粉分析和公布的记录来确定，而磁化率、电阻率、有机物含量和粒度的实验室分析将用于确定飓风生成的地层。年代控制将通过放射性碳测年。将替代飓风记录扩展到未经研究的加勒比地区将有助于更清楚地了解区域基础上的长期飓风行为，而将飓风和气候记录联系起来将有助于我们更好地了解两者之间的关系。调查飓风活动作为一个互动的组成部分，更大的环流模式有利于解开复杂的连接。自1990年代中期以来，飓风路径的频率和位置发生变化，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位置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对不断变化的气候条件作出反应的方式，是对这一严重自然灾害作出有效社会反应的关键一步。

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.