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

该项目将利用资金开展一系列耦合同位素模拟实验、数据收集和数据模型比较，以提供全新世气候变化的新见解，重点是水文循环。要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)这些变化的降水和海水同位素特征是什么？3)日晒强迫的水文循环变化是否影响高纬度地区的深层或中层产水？4)与8.2 ka事件相关的陆相水同位素和海水d18O （d18Osw）异常的气候响应空间特征与哈德逊海峡淡水输入是否一致？5)日晒变化和持续的enso样气候模式对全球气候的综合影响是什么？在古水同位素档案中是否观察到这种变化？6)与气候系统长期内在变化（即非强迫年代际NAO或温盐变化）相关的模式是什么？为了解决这些问题，将进行海洋-大气耦合全球环流模式（AOGCM）的模拟。这些措施包括适当的日照、剩余的陆地冰，以及一项8,200年的实验，通过添加淡水作为对照运行的基本情况。通过AGCM实验，探讨持续厄尔尼诺-南方涛动（ENSO）事件的影响以及AOGCM与数据显著差异的原因。轨道强迫气候的瞬态行为，包括同位素记录，将使用一个采用加速轨道强迫的长时间耦合实验来评估。这项工作还将产生新的数据（基于镁/钙的海面温度估计和浮游有孔虫氧同位素），这些数据将与冰芯、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一起使用，以验证模型的输出。哥伦比亚大学和伍兹霍尔海洋学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将提交到公共资助的基于web的数据存储库。

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.