Millennial-scale Tropical Rainfall Variability From 100 to 20 ka: Testing Cross-Isthmian Water Vapor Transport and Feedbacks on Thermohaline Circulation

该项目调查了洞穴沉积物的效用（即，洞穴沉积物）作为一种手段，开发气候代用数据，有助于限制千年时间尺度上的陆地降雨量变化，并具有足够的时间分辨率，以评估与海洋温盐环流有关的可能的热带反馈机制。 一般的科学目标是通过评估降雨量来限制热带水文循环，作为跨地峡水蒸气输送的代理，以及记录过去10万年的热带气候变化。（十年到多十年）氧同位素时间序列，热带降雨量的代理，来自哥斯达黎加和墨西哥石笋的铀系列，目前受热带辐合带（ITCZ）影响的地点。 指导性的科学假设是，末次冰期的热带降雨主要受千年尺度的Dansgaard/Oeschger（D/O）变率的影响，而这种变率是由热带大西洋的温盐环流变率和海面温度造成的。 研究人员还假设，海因里希事件与ITCZ向南移位导致中美洲降雨不足有关。

This project investigates the utility of speleothems (i.e., cave deposits) as a means to develop climate proxy data that could help constrain terrestrial rainfall variability, on millennial time scales, with sufficient temporal resolution to evaluate a possible tropical feedback mechanism related to oceanic thermohaline circulation. The general science goals are to constrain the tropical hydrological cycle through evaluation of rainfall amount as a proxy for cross-isthmian water vapor transport, as well as document tropical climate variability over the last 100,000 years.Specifically, the research team will work to generate high resolution (decadal to multidecadal) oxygen isotope time series, a proxy for tropical rainfall amount, from Uranium series dated stalagmites from Costa Rica and Mexico, sites that are currently under the influence of the Intertropical Convergence Zone (ITCZ). The guiding scientific hypothesis is that tropical rainfall during the last glacial period is dominated by millennial-scale Dansgaard/Oeschger (D/O) variability, which is forced by thermohaline circulation variability and sea surface temperatures in the tropical Atlantic Ocean. The researchers also hypothesize that Heinrich events are associated with deficient rainfall over Central America resulting from a southward displacement of the ITCZ.