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地方、区域和全球气候制度可能发生的重大变化之间的关系的辩论。基于仪器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。古风暴学可以依靠替代记录来克服仪器记录的局限性，并有助于确定在现代记录中不明显的飓风频率变化。该博士论文研究项目将通过对沿海湖泊沉积物岩心的地层学分析，定量评估和描述飓风唐娜对加勒比海北部三个岛屿的地貌和沉积学影响，从而建立第一个广泛的古风暴学现代模拟研究。1960年，飓风“唐娜”以4级飓风的强度直接袭击了巴布达、安圭拉、阿克林斯岛（巴哈马群岛）等加勒比海岛国，随后登陆佛罗里达州南部，肆虐美国大西洋沿岸，沿途造成了巨大的破坏和人员伤亡。这项研究将验证唐娜在三个加勒比岛屿上造成了一次冲过事件的假设，这将在沿海后屏障湖的沉积物中留下可探测的冲过沙层记录。唐娜的地层记录将与近期其他已知强度的飓风的地层记录进行比较，这些飓风也影响了岛屿，这样就可以建立飓风强度与代理信号强度（如沙层厚度）之间的现代关系。利用多种地质和生物代用品，结合放射性同位素定年（14C和137c），确定飓风唐娜的地层特征，并用于校准史前飓风袭击的代用品记录，努力重建北加勒比地区晚全新世的飓风活动历史。对加勒比海北部长期飓风历史的重建，与加勒比海其他地区正在进行的古风暴学研究相结合，将有助于解释飓风模式在整个盆地范围内的变化，进而可以用来破译它们背后的强迫机制。该项目意义重大，因为它建立了一种全面的现代模拟方法，对代用记录的校准和解释至关重要，为年轻的古风暴学科学做出了贡献。该项目还将建立加勒比海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巨大空白。这些来自加勒比海北部的新代用记录对于检验百慕大高压假说至关重要，该假说是古风暴学新兴领域的基石。这项研究有许多实际应用，对加勒比地区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时空变异性以及造成这种变异性的气候机制。这项研究将产生长期的代理记录，这些记录对于计算北加勒比地区的飓风回归期和每年登陆概率是必要的。这些数据具有巨大的社会价值，可被地方政府官员用于风险评估和减灾规划。当地研究人员和学校学生参与实地考察也将有助于这些加勒比岛屿国家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.