Collaborative Research: P2C2--Testing the Tropical Storm and Tropical Cyclone Masking Hypotheses: Advancing Speleothem Reconstruction of Paleotempestology and Paleohydrology

该项目旨在利用尤卡坦半岛洞穴中的洞穴化石重建影响加勒比海和墨西哥湾地区数十万年的定量降水和热带气旋（TC）记录。这种重建的成功取决于了解当地降水量与降水δ 18-氧同位素值之间的关系（即数量效应）以及这种关系如何在石笋矿床中保存。TC降水可以改变数量效应，因此有假设认为TC降雨可能会影响定量石笋δ 18-氧同位素降水记录（即TC掩蔽假说）。然而，最近基于石笋三角洲18氧同位素降水记录的研究表明，温度变化与古玛雅文明的崩溃有关（即热带风暴假说）。可用于验证这一假设的石笋三角洲18-氧同位素降水记录尚未被复制，其降水估计可能反映了TC遮蔽。此外，时间的不确定性、缺乏平衡的石笋三角洲18-氧同位素值和区域气候变率可能会阻碍复制。因此，研究人员将：(i)应用一种有前途的方法，在过去2000年的选定间隔内复制现有的石笋三角洲18-氧同位素降水记录；（ii）定量地检验TC掩蔽对数量效应和石笋降水记录的影响；（iii）通过采用超高分辨率采样方法检测三个已知石笋（即CH-1， Chaac, Itzamna）中单个tc的特定同位素特征来验证热带风暴假说。潜在的更广泛的影响包括提高对不同气候状态和长时间尺度下热带气旋-气候关系的认识。这种了解对于在不断变化的气候下进行准确预测以及评估和减轻气候变化风险至关重要。本项目资助一名本科文理学院的女首席研究员。它将为一些本科生提供重要的研究经验，研究人员在支持女性和代表性不足的少数民族学生方面有着悠久的历史。其中一名主要研究人员是一名早期的西班牙裔教师，这个项目将支持这位研究人员和两名西班牙裔女博士生的工作。这项工作可能有助于进一步发展基于洞穴的古风暴学方法，并强调在其他热带洞穴记录中考虑TC掩蔽的必要性。最后，这项工作将引起考古研究界的兴趣，因为它可以帮助解决tc在拉丁美洲社会变革中的作用。

This project aims to use speleothems from caves on the Yucatan Peninsula to reconstruct quantitative precipitation and tropical cyclone (TC) records affecting the Caribbean and Gulf of Mexico regions spanning hundreds of thousands of years.The success of such reconstructions depends on understanding the relationship between local precipitation amount and precipitation delta 18-Oxygen isotope values (i.e. the amount effect) and how this relationship is preserved in stalagmite deposits. TC precipitation can shift the amount effect and it has been hypothesized that TC rain may therefore bias quantitative stalagmite delta 18-Oxygen isotope precipitation records (i.e. the TC masking hypothesis). Recent studies based on stalagmite delta 18-Oxygen isotope precipitation records, however, suggest that TC variability was linked to the collapse of the ancient Maya civilization (i.e., the tropical storm hypothesis). Available stalagmite delta 18-Oxygen isotope precipitation records to test this hypothesis have not yet been replicated and their precipitation estimates may reflect TC masking. Replication, furthermore, may be hindered by chronological uncertainty, the lack of equilibrium stalagmite delta 18-Oxygen isotope values and regional climate variability. The researchers therefore will: (i) apply a promising approach for replication of available stalagmite delta 18-Oxygen isotope based precipitation records during selected intervals spanning the last 2000 years; (ii) examine quantitatively the TC masking influence on the amount effect and on stalagmite precipitation records; and (iii) test the tropical storm hypothesis by applying an ultrahigh resolution sampling approach to detect the particular isotopic signature from individual TCs in three known stalagmites (i.e., CH-1, Chaac, Itzamna).The potential Broader Impacts include improved understanding of tropical cyclone (TC)-climate relationships under different climate states and over long timescales. Such understanding is critical for accurate projections and TC risk assessment and mitigation in a changing climate. This project supports a female lead investigator at an undergraduate liberal arts college. It will provide significant research experience for several undergraduates and the researchers have a strong history of supporting women and underrepresented minority students. One of the lead researchers is an early-career Hispanic faculty member and this project would support the work of this researcher and two female Hispanic PhD students. This work would potentially help further develop methods for speleothem-based paleotempestology and would highlight the need to consider TC masking in other tropical speleothem records. Finally, this work will be of interest to the archaeology research community as it can help address the role of TCs in societal changes in Latin America.