Collaborative Research: Water Isotope Model-Data Comparison for Holocene Climate Variability

该项目将利用资金开发一系列耦合的同位素模拟实验、数据收集和数据模型比较，以提供对全新世气候变化的新见解，重点是水文循环。有待解决的科学问题包括：1)全新世期间水文循环对日照变化的响应是什么？2)这些变化在降水和海水中的同位素特征是什么？3)水循环中日照强迫的变化是否影响高纬度的深层或中层水的生产？4)气候响应的空间特征，包括陆地水同位素和海水的d18O(D18Osw)异常，是否与8.2 ka事件与输入淡水到哈德逊海峡相一致？5)日照变化和持续的类似ENSO的模式对全球气候的综合影响是什么在古水同位素档案中观察到这样的变化吗？和6)气候系统的长期内在变化(即非强迫年代际NAO或温盐变化)有哪些相关模式？为了解决这些问题，将进行海-气耦合全球环流模式(AOGCM)模拟。这些措施将包括适当的日照、残留的陆地冰，以及通过添加淡水作为对照运行的基本情况的8200年实验。持续的厄尔尼诺-南方涛动(ENSO)事件的影响以及AOGCM与数据之间显著差异的原因将通过AGCM实验进行探索。轨道强迫气候的瞬变行为，包括同位素记录，将通过一个采用加速轨道作用力的长期耦合实验来评估。这项工作还将产生新的数据(基于镁/钙的海表面温度估计和浮游有孔虫氧同位素)，这些数据将与来自冰芯、湖泊、洞穴和珊瑚的水同位素记录以及现有的海洋同位素海水成分记录结合使用，以验证模型输出。哥伦比亚大学和伍兹霍尔海洋研究所的几名研究生将得到这项研究的支持，并通过与多个机构的研究人员互动而受益。所有新数据、数据合成和模型模拟都将提交给公共资助的基于网络的数据储存库。

This project will use funds to develop a series of coupled isotope modeling experiments, data collection, and data model comparisons to provide new insights into Holocene climate change, with an emphasis on the hydrologic cycle. Science questions to be addressed include: 1) What was the response of the hydrologic cycle to insolation changes during the Holocene? 2) What was the isotopic signature in precipitation and ocean waters of these changes? 3) Did insolation-forced changes in the hydrological cycle influence deep or intermediate water production in the high latitudes? 4) Is the spatial signature of the climate response, including terrestrial water isotope and d18O of seawater (d18Osw) anomalies, associated with the 8.2 ka event consistent with input of freshwater into the Hudson Strait? 5) What are the combined effects of insolation changes and persistent, ENSO-like patterns on global climate, and are such changes observed in paleo-water isotope archives? and 6) What are the patterns associated with long-term intrinsic variations of the climate system (i.e. unforced decadal NAO or thermohaline variability)?To address these questions, coupled ocean-atmosphere global circulation model (AOGCM) simulations will be performed. These are to include appropriate insolation, residual land ice, and an 8,200-year experiment by adding freshwater as the base case for the control run. The effect of sustained El Nino-Southern Oscillation (ENSO) events and the cause of significant discrepancies between AOGCM and data will be explored with AGCM experiments. Transient behaviors of orbitally forced climate, including isotope records, are to be evaluated using one long coupled experiment employing accelerated orbital forcing.The work will also generate new data (Magnesium/Calcium-based sea surface temperature estimates and planktonic foraminifera oxygen isotopes) to be used in conjunction with water isotope records from ice cores, lakes, speleothems, and corals, and existing marine isotope seawater composition records to validate model output.Several graduate students at Columbia University and the Woods Hole Oceanographic Institute will be supported by this research and benefit by interacting with researchers at multiple institutions. All new data, data syntheses, and model simulations will be submitted to publicly funded web based data repositories.