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

这个项目的目的是利用尤卡坦半岛洞穴中的洞穴来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对当地降雨量和降水三角洲18氧同位素值之间的关系(即量效应)的理解，以及这种关系如何在石笋沉积物中得到保存。热带气旋降水可以改变降水的数量效应，因此假设热带气旋降水可能会偏离定量的石笋三角洲18氧同位素降水记录(即气旋掩蔽假说)。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，TC的变异性与古代玛雅文明的崩溃(即热带风暴假说)有关。现有的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，它们的降水量估计可能反映了TC的掩盖。此外，年代学的不确定性、缺乏平衡的石笋三角洲18氧同位素值和区域气候变异性可能会阻碍复制。因此，研究人员将：(I)应用一种有希望的方法来复制过去2000年选定时间间隔内现有的石笋三角洲18氧同位素降水记录；(Ii)定量检查TC对数量效应和石笋降水记录的影响；以及(Iii)通过应用超高分辨率采样方法来检测三种已知石笋(即CH-1、CHAc、Itzamna)中单个TC的特殊同位素特征，以检验热带风暴假说。更广泛的影响包括更好地理解热带气旋(TC)-不同气候状态下和长时间尺度下的气候关系。这种了解对于气候变化中的准确预测和TC风险评估和缓解至关重要。该项目支持一名本科文科学院的女性首席研究员。它将为几名本科生提供重要的研究经验，研究人员在支持女性和代表不足的少数族裔学生方面有很强的历史。主要研究人员之一是一名职业生涯早期的西班牙裔教员，该项目将支持这名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以洞穴群为基础的古温度学方法，并将突出在其他热带洞穴群记录中考虑TC掩蔽的必要性。最后，这项工作将引起考古学研究界的兴趣，因为它可以帮助解决TCS在拉丁美洲社会变化中的作用。

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.