Doctoral Dissertation Research: Tracking Donna Across the Northern Caribbean: Developing a Modern Analog Methodology for Paleotempestology

2005年极具破坏性的飓风季节加剧了关于飓风和其他严重风暴的数量和强度与当地、区域和全球气候制度可能发生重大变化的程度的辩论。以仪器为基础的气候记录只存在于相对较近的时期，这一事实阻碍了研究历史趋势的努力。古风温学可以依靠替代记录来克服仪器记录的局限性，并有助于识别在现代记录中不明显的飓风频率变化。这一博士论文研究项目将通过对沿海湖泊沉积岩心的地层分析，定量评估和描述飓风唐娜对北加勒比海三个岛屿的地貌和沉积学影响，从而建立第一个广泛的现代古温学模拟研究。1960年，飓风唐娜作为4级飓风直接袭击了加勒比海岛国巴布达、安圭拉和阿克林斯岛，然后在佛罗里达州南部登陆，肆虐美国大西洋海岸，造成沿途巨大的破坏和人员伤亡。这项研究将检验这样一种假设，即唐娜在加勒比海三个岛屿中的每一个都造成了溢流事件，这将在沿海屏障后湖泊的沉积物中以溢流沙层的形式留下可检测的记录。唐娜的地层记录将与最近也影响岛屿的已知强度飓风的地层记录进行比较，以便建立飓风强度与替代信号强度(例如沙层厚度)之间的现代关系。利用多种地质和生物指标结合放射性同位素测年(14C和137Cs)，将确定唐娜飓风的地层特征，并用于校准史前飓风袭击的指标记录，以努力重建加勒比北部飓风活动的晚全新世历史。重建加勒比北部的长期飓风历史，将结合加勒比其他地区正在进行的其他古温学研究，解释整个盆地飓风模式的变化，进而可用来破译飓风背后的强迫机制。这一项目意义重大，因为它通过建立一种对校准和解释替代记录至关重要的全面的现代模拟方法，为年轻的古温学科学做出了贡献。该项目还将建立加勒比北部史前飓风袭击的第一个代理记录，从而填补目前大西洋古飓风知识和数据网络的一大空白。来自加勒比海北部的这些新的代理记录将对检验百慕大高压假说至关重要，百慕大高压假说是新兴的古温学领域的基石。这项研究有许多实际应用，它们对加勒比区域的社会具有深远的意义。迫切需要了解加勒比地区飓风活动的空间和时间变异性以及造成这种变异性的气候机制。这项研究将产生计算加勒比北部地区飓风重现期和年度登陆概率所必需的长期替代记录。这些数据具有很大的社会价值，可供地方政府官员用于风险评估和缓解规划。当地研究人员和在校学生参与实地考察工作也将有助于这些加勒比岛国的科学教育和能力建设。

The highly destructive hurricane season of 2005 intensified debate regarding the degree to which the number and intensity of hurricane and other severe storms were related to possibly significant changes in local, regional, and global climatic regimes. Attempts to study historical trends have been hampered by the fact that instrument-based climate records have existed only in relatively recent time periods. Paleotempestology can look to the proxy record to overcome the limitations of the instrumental record and can help to identify hurricane frequency changes that are not evident in the modern record. This doctoral dissertation research project will establish the first extensive modern analog study for paleotempestology by quantitatively assessing and characterizing the geomorphic and sedimentological impacts of Hurricane Donna across three northern Caribbean islands via the stratigraphic analysis of coastal lake sediment cores. Hurricane Donna directly struck the Caribbean island nations of Barbuda, Anguilla, and Acklins Island (Bahamas) as a severe category 4 hurricane in 1960 before making landfall in southern Florida and ravaging the U.S. Atlantic coast, causing tremendous destruction and casualties along its path. This study will test the hypothesis that Donna caused an overwash event in each of the three Caribbean islands, which would have left a detectable record in the form of overwash sand layers in the sediments of coastal back-barrier lakes. The stratigraphic record of Donna will be compared with those of other recent hurricanes of known intensities that also impacted the islands, so that the modern relationship between hurricane intensity and proxy signal strength (e.g., sand layer thickness) can be established. Using multiple geological and biological proxies in concert with radio-isotopic dating (14C and 137Cs), the stratigraphic signature of Hurricane Donna will be identified and used to calibrate the proxy records of prehistoric hurricane strikes in an effort to reconstruct a late-Holocene history of hurricane activities for the northern Caribbean. The reconstruction of a long-term hurricane history for the northern Caribbean will allow, in conjunction with other ongoing paleotempestological studies in other parts of the Caribbean, for the interpretation of basin-wide shifts in hurricane patterns that in turn can be used to decipher the forcing mechanisms behind them. This project is significant as it contributes to the young science of paleotempestology by establishing a comprehensive modern analog methodology that is essential to the calibration and interpretation of the proxy records. This project will also establish the first proxy records of prehistoric hurricane strikes for the northern Caribbean, thereby filling a large gap in the current knowledge and data network for Atlantic paleohurricanes. These new proxy records from the northern Caribbean will be vital for testing the Bermuda High Hypothesis, which is a cornerstone in the burgeoning field of paleotempestology. There are many practical applications for this study and they have far reaching relevance to the societies of the Caribbean region. There is a pressing need to understand the spatial and temporal variability of hurricane activity in the Caribbean and the climate mechanisms responsible for this variability. This study will produce long-term proxy records that are necessary for the calculation of hurricane return periods and annual landfall probabilities for the northern Caribbean region. These data have great societal value and can be used by local government officials in risk assessment and mitigation planning. Involvement of local researchers and school students in fieldwork will also contribute to science education and capacity building in these Caribbean island nations.