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

该项目旨在从现有的环状柚木(Tectona Grand is L.f.)中提取纤维素，开发三角洲氧-18同位素数据系列。来自印度尼西亚南苏拉威西岛穆纳的树芯样本。初步结果表明，MUNA OORT-18是ENSO相关降水变化的一个指标，但具有较高的信噪比。由于Muna收集包含多达44个交叉测年增量岩芯，研究人员将在1656-2005年的样品上使用每年6次重复的年度分辨率的同位素采样。这是一个350年的间隔，涵盖了工业化前和人为的温室气体和土地覆盖/土地利用变化的强迫水平，火山和太阳爆炸强迫的多次实现，以及净强迫最小的年份。将使用气象数据、新的降水氧-18同位素数据集合和参数敏感性研究，对同位素数据的解释与现有的代理传感器模型进行测试。将利用对同一时间间隔估计的外部辐射作用力的估计，得出复合纤维素、氧-18同位素反应和不确定度估计。研究人员将对非强迫年份、火山事件年份、太阳强迫年份以及前工业化、过渡性和人为的气溶胶、土地利用/变化和温室气体强迫时间窗口进行叠加历元分析，以检验推断的ENSO事件返回间隔和幅度的零差异。潜在的更广泛影响包括可能提供一种新的分析技术，适用于相对未开发和潜在关键的热带气候档案，支持美国指导的马里兰大学本科生的国际研究经验，以及对研究生的支持这一奖项反映了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 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.