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

该项目特别寻求使用从危地马拉、洪都拉斯、厄瓜多尔、秘鲁、玻利维亚和智利树木的年轮中测量的稳定氧同位素(δ18O)来重建至少过去200年整个新热带地区的雨季降水变异性，以收集关于大规模热带气候动态的见解。这项研究的总体目标是了解热带辐合带(ITCZ)位置和宽度最近和未来可能发生的变化，以及这些变化如何与全球气候变率模式联系在一起，并可能影响北半球(NH)和南半球(SH)的热带降水模式。采用来自树木纤维素的同位素的研究策略的合理性在于，热带地区(大面积地理区域和广泛的生态系统)树轮记录的相对匮乏阻碍了对气候变异性范围的更全面的了解，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。这样的数据无法从世界其他地方的现代观测、先导研究和古气候数据中获得。潜在的更广泛的影响包括对参与研究的博士后研究员和本科生的支持以及与国际研究人员的广泛互动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.