Collaborative Research: P2C2--Hydroclimatic Response of El Nino-Southern Oscillation to Natural and Anthropogenic Radiative Forcing

该项目旨在从印度尼西亚南苏拉威西岛穆纳现有的有年轮年代的柚木 (Tectona grandis L. f.) 树芯样本中提取的纤维素开发 δ 氧 18 同位素数据系列。 初步结果表明，Muna Oxy-18 是 ENSO 相关降水变化的指标，但具有较高的信噪比。由于 Muna 收藏包含多达 44 个交叉日期的增量岩心，因此研究人员将对 1656 年至 2005 年的可用样本进行年度分辨率的同位素采样，每年重复 6 次。 这是一个 350 年的间隔，跨越前工业化和人为温室气体和土地覆盖/土地利用变化强迫水平、爆炸性火山和太阳强迫的多次实现，以及净强迫最小的年份。将使用气象数据、新收集的降水氧 18 同位素数据和参数敏感性研究，根据现有的代理传感器模型来测试同位素数据的解释。复合纤维素氧 18 同位素响应和不确定性估计将使用对相同时间间隔估计的外部辐射强迫的估计来得出。研究人员将使用非受迫年份、火山事件年、太阳强迫几十年以及工业化前、过渡和人为时间窗的气溶胶、土地利用/变化和温室气体强迫的叠加历元分析来测试推断的 ENSO 事件返回间隔和幅度的零或无差异。潜在的更广泛影响包括可能提供一种新的分析技术，应用于相对未开发和潜在关键的热带气候档案，美国的支持。为马里兰大学研究生和顶点本科生提供国际研究经验指导，并为研究生提供支持。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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 aims to develop delta oxygen-18 isotope data series from cellulose extracted from an existing collection of ring-dated teak (Tectona grandis L. f.) tree core samples from Muna, South Sulawesi, Indonesia. Preliminary results suggest that Muna oxygen-18 is an indicator of ENSO-related precipitation variation, but with a higher signal-to-noise ratio. Because the Muna collection contains up to 44 cross-dated increment cores, the researchers will use isotopic sampling at annual resolution with 6 replicates per year, on samples available for the years 1656-2005. This is a 350-year interval spanning both pre-industrial and anthropogenic greenhouse gas and land cover/land use change forcing levels, multiple realizations of explosive volcanic and solar forcing, and years for which net forcing is minimal.Interpretation of the isotopic data will be tested against existing proxy sensor models using meteorological data, a new collection of precipitation oxygen-18 isotope data, and parameter sensitivity studies. Composite cellulose oxygen-18 isotope response and uncertainty estimates will be derived using estimates of the external radiative forcings estimated for the same time interval. The researchers will test the null of no difference in inferred ENSO event return interval and amplitude using superposed epoch analysis for unforced years, volcanic event years, solar-forced decades, and pre-industrial, transitional and anthropogenic time windows for aerosol, land use/change and greenhouse gas forcings.The potential Broader Impacts include possibly providing a new analytical technique to apply to relatively untapped and potentially critical climate archives of the tropics, support of U.S. mentored international research experiences for graduate and capstone undergraduate students at the University of Maryland, as well as support for a graduate studentThis 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.