Collaborative Research: Intertropical Convergence Zone Variations from Stable Oxygen Isotope Tree-ring Records in the Tropical Americas

该项目旨在利用从危地马拉、洪都拉斯、厄瓜多尔、秘鲁、玻利维亚和智利的树木年轮中提取的纤维素中测量到的稳定氧同位素（δ18O），重建至少过去200年来新热带地区雨季降水的变化，以收集有关大尺度热带气候动态的信息。研究的总体目标是了解热带辐合带（ITCZ）的位置和宽度最近和潜在的未来变化，以及这些变化如何与全球气候变率模式联系起来，并可能影响北半球（北半球）和南半球（南半球）的热带降雨模式。使用来自树木纤维素的同位素的研究策略的理由是，热带地区（一个大的地理区域和广泛的生态系统）树木年轮记录的相对缺乏阻碍了对气候变率范围的更全面的理解，特别是在十年到百年的时间尺度上以及对辐射强迫变化的响应。否则，这些数据无法从世界其他地方的现代观测、初步研究和古气候数据中获得。潜在的更广泛的影响包括支持博士后研究人员以及参与研究的研究生本科生以及与国际研究人员的广泛互动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project specifically seeks to use stable oxygen isotopes (δ18O) measured in cellulose from the annual growth rings of trees located in Guatemala, Honduras, Ecuador, Peru, Bolivia and Chile to reconstruct wet season precipitation variability for at least the last 200 years across the neotropics to glean insights on large-scale tropical climate dynamics. The general goal of the research is to understand recent and potential future changes in the position and width of the Intertropical Convergence Zone (ITCZ) and how these changes may be tied to global modes of climate variability and could affect patterns of tropical rainfall in both the northern (NH) and southern (SH) hemispheres.The rational for the research strategy of using isotopes from tree cellulose is that the relative paucity of tree-ring records in tropical regions (a large geographic area and extensive ecosystem) prevents a more comprehensive understanding of the range of climate variability particularly at decadal to centennial time scales and in response to changes in radiative forcing. Such data are otherwise unavailable from modern observations, pilot studies, and paleoclimate data elsewhere in the world.The potential Broader Impacts include support for a postdoctoral researcher as well as graduate undergraduate students involved in the research and extensive interaction with international researchers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.