P2C2:Collaborative Research: A Speleothem Study of the Paleoclimatology of the Yucatan Peninsula: Testing Modes and Causes of Variability in the North American Tropics

该项目的目标是重建低纬度降水变化，从年际到轨道时间尺度，以更好地了解尤卡坦半岛（YP）中尺度和大尺度大气和海洋动力、外部强迫和反馈的水文响应。目前提出的驱动该地区亚轨道尺度气候的机制包括ENSO、热带气旋形成和与热带辐合带（ITCZ）运动相关的降水变化，但现有的古气候记录在成因方面存在矛盾。该项目可能潜在地改善降雨敏感性估计，这将代表独立于模型的经验评估。目前国际气候模式对该地区到本世纪末降水变化的估计在一个很大的范围内变化（与今天相比-50%至+9%）。该项目还将支持一名未被充分代表的少数族裔早期职业科学家，并为几名本科生提供早期研究经验。此外，研究小组将制作西班牙文和英文版本的教育材料和展品，供一般观众使用。研究小组将利用YP洞穴的洞穴化石重建该地区在全新世、末次冰期、海洋同位素阶段（MIS） 5和MIS 7至9期间的水文变化特征。特别是，该团队将根据石笋中的δ -18氧同位素对降水变化进行定量重建。结合YP现有的湖泊记录，当地的洞穴记录可能为定量重建该地区的降水与蒸发平衡提供了独特的机会。全新世和晚更新世的定量高分辨率降水记录将：1)提供过去降雨变率的定量估计；2)检验降水变率与平均ITCZ变化的关系；3)研究ENSO、热带海表温度和气旋对YP气候变化的影响；4)提供对热带水文敏感性的估计。研究人员将利用与里约热内卢秘密保护区的积极合作，里约热内卢秘密保护区是一家商业企业，带领约5万名游客通过YP东海岸的一个大型，部分淹没的洞穴系统进行教育和推广。里约热内卢Secreto洞穴系统代表了一个理想的洞穴系统，用于重建该地区大约30万年以前的石笋降水变化。

This project's goal is to reconstruct low latitude precipitation variability, from interannual to orbital time scales, to better understand hydrological responses to meso and large-scale atmosphere and ocean dynamics, external forcing, and feedbacks in the Yucatan Peninsula (YP). The mechanisms proposed for driving suborbital scale climate regimes in the region include ENSO, tropical cyclogenesis and shifts in precipitation associated with movements of the Inter Tropical Convergence Zone (ITCZ), but available paleoclimate records are contradictory in terms of causal factors.The project could potentially improve rainfall sensitivity estimates that would represent an empirical assessment independent of models. Current international climate model estimates of precipitation changes in the region by the end of this century vary over a significant range (-50% to +9% relative to today). The project would also support an underrepresented minority early-career scientist and provide an early experience in research to several undergraduate students. In addition, the research team will produce educational materials and exhibits for a general audience in Spanish and English language versions.The research team will use speleothems from caves of the YP to reconstruct the character of hydrological variability in the region during the Holocene, the last glacial interval, marine isotope stage (MIS) 5, and MIS 7 to 9. In particular, the team will make quantitative reconstructions of precipitation changes based on delta-18Oxygen isotopes in stalagmites. In combination with available lacustrine records from the YP, local speleothem records may provide a unique opportunity to quantitatively reconstruct the precipitation to evaporation balance in the region. Quantitative high-resolution Holocene and Late Pleistocene precipitation records will: 1) provide quantitative estimates of past rainfall variability; 2) test the relationship between rainfall variability and shifts in mean ITCZ; 3) investigate the role of ENSO, tropical sea surface temperatures and cyclones in driving climate regimes in the YP; and 4) provide estimates of the sensitivity of tropical hydrology.The researchers will leverage an active collaboration with the Rio Secreto Reserve, a commercial enterprise that leads ~50,000 tourists through a large, partially submerged cave system on the east coast of the YP for education and outreach aims. The cave system of Rio Secreto represents an ideal cave system for reconstructing precipitation changes from stalagmites in the region extending approximately 300,000 years before the present.