Collaborative Research: Common Era Climate Variability from Marine Proxy Surrogate Reconstructions

密度驱动的大西洋经向翻转环流(AMOC)可以在区域和全球尺度上影响气候，但很难受到简短观测记录的限制。这增加了对现代气候趋势的解释和对未来变化的预测的相当大的不确定性。拟议的工作将通过在海洋-大气耦合大气环流模式(AOGCM)模拟的物理一致框架内对过去2000年的AMOC变率进行定量重建来扩展仪器记录。该项目将确定从代理数据中出现的AMOC变异性的重要模式及其最可能的原因。合成的假代理人将被用来评估这些结果的技能，并确定可能减少未来不确定性的地点。这项工作的结果将为自然AMOC-气候关系提供有价值的基线，为未来气候变化预测提供最新趋势的背景。这项研究将结合一个跨越过去两千年的海洋代理记录网络，该网络是在PAGE Ocean 2k倡议的第一阶段汇编的，与气候模型比对项目(CMIP)同位素相结合，使AOGCMS能够使用代理代理重建(PSR)来估计AMOC。PSR方法中由方法选择、数据类型、代理分布和观测误差引起的不确定性将部分基于伪代理实验(PPEs)进行评估。PSR代表完全一致的物理系统，允许熟练的PSR中的AMOC强度和模式与大气环流、外部辐射强迫和其他变量进行比较，以评估它们的动力学联系。随着代理网络在未来的扩展，对PSR的信心可能会增加，PPE将用于确定其他位置，从这些位置获得的额外数据可能会减少基于PSR的AMOC(和其他变量)估计的不确定性，从而为未来的工作提供目标。除了推进国际海洋2K和模型相互比较项目努力具有更广泛的科学意义外，其他显著影响还包括支持一名没有国家科学基金会事先支助的早期职业研究人员，为本科生提供研究机会，两名研究人员都参与了针对少数群体和高中生的当地教育倡议。

The density-driven Atlantic meridional overturning circulation (AMOC), which can influence climate on regional and global scales, is poorly constrained by brief observational records. This adds considerable uncertainty to the interpretation of modern climate trends and to forecasts of future change. The proposed work will extend the instrumental record by generating quantitative reconstructions of AMOC variability over the past 2,000 years within the physically consistent framework of coupled ocean-atmosphere general circulation model (AOGCM) simulations. The project will identify the significant patterns of AMOC variability that emerge from proxy data and their most likely causes. Synthetic pseudoproxies will be used to evaluate the skill of these results and identify sites that might reduce uncertainty in the future. Results from this work will provide a valuable baseline for natural AMOC-climate relationships, giving context to recent trends that will inform future climate change forecasts. The research will combine a network of marine proxy records spanning the past two millennia, compiled during Phase 1 of the PAGES Ocean2K initiative, with Climate Model Intercomparison Project (CMIP) isotope enabled AOGCMs to estimate AMOC using proxy surrogate reconstructions (PSRs). The uncertainty in the PSR method arising from methodological choices, data type, proxy distribution and observational error will be evaluated based, in part, on pseudoproxy experiments (PPEs). PSRs represent completely consistent physical systems, allowing AMOC strength and pattern in skillful PSRs to be compared with atmospheric circulation, external radiative forcing and other variables to evaluate their dynamical links. Confidence in PSRs will likely increase as the proxy network expands in the future, and a PPE will be used to identify additional locations from which additional data might reduce the uncertainty in PSR-based estimates of AMOC (and other variables), providing a target for future work. In addition to the broader scientific relevance of advancing the international Oceans2K and model intercomparison project efforts, other notable impacts include support of an early career researcher with no prior NSF support, research opportunities for undergraduates, and involvement of both researchers in local education initiatives for minorities and high school students.