Ocean Circulation and Climate Impacts of Proglacial Lake Outbursts into the Northeastern Pacific Ocean

许多模型已经探讨了北大西洋淡水洪水事件在上一个冰期末突然气候变化的背景下的影响，表明这些事件对经向翻转环流(MOC)系统产生了重大影响。在早期的冰川消融期间(大约公元前16,600到13,000年)，来自盛冰期的米苏拉湖的灾难性洪水淹没了华盛顿-俄勒冈州东部，并通过卡斯卡迪亚盆地进入太平洋。虽然我们知道这些洪水产生的浑浊洋流深入北太平洋近1000公里，深度超过3公里，但人们对这种淡水排放对海洋环流或气候的影响知之甚少。与北大西洋不同，向东北太平洋排放淡水最有可能对气候产生影响，这涉及到上层海洋结构和温跃层性质的变化。该项目将进行模拟实验(理想化的纯海洋和全耦合的CCSM3模式模拟)，以探索表层排放事件与来自超高温次表层气流的对流的影响，以检验洪水引起的北太平洋亚极-副热带海洋环流变化可能影响热带辐合带(ITCZ)位置的假设，从而提供通过热带海-气相互作用影响气候的机制。该项目还将使用放射性碳测年核心材料来建立爆发事件的年表。拟议工作的广泛影响该项目将加强物理海洋学家、古海洋学家和古气候学家之间的合作。太平洋西北更新世洪水是一个公众非常感兴趣的现象，因为它们极大地影响了区域的大部分景观。拟议的研究结果将用于通过与冰川时代所见变化的联系，教育公众了解当今气候变化的过程。一位年轻的女性博士后将从地球科学领域的三位顶尖科学家那里接受宝贵的跨学科培训。

Numerous models have explored the impact of North Atlantic freshwater flood events in the context of abrupt climate change at the end of the last ice age, suggesting these events had major impact on the meridional overturning circulation (MOC) system. During the early deglaciation (roughly 16,600 to 13,000 BC), cataclysmic floods from proglacial Lake Missoula inundated eastern Washington-Oregon and passed into the Pacific Ocean via the Cascadia Basin. While we know that turbidity currents originating from these floods penetrated nearly 1000 km into the North Pacific to depths over 3km there is little understanding of the impact of this freshwater discharge on ocean circulation or climate. Unlike the North Atlantic, the most likely scenario for climate impact from freshwater discharge into the Northeast Pacific involves changes in structure of the upper ocean and thermocline properties. This project will conduct modeling experiments (idealized ocean-only and fully-coupled numerical CCSM3 model simulations) to explore the impacts of a surface layer discharge event versus convection from a hyperpycnal, subsurface flow to test the hypothesis that flood induced changes in N. Pacific subploar-subtropical ocean circulation could influence the position of the intertropical convergence zone (ITCZ), thereby providing a mechanism for influencing climate via tropical air-sea interaction. The project will also use radiocarbon date core material to establish a chronology of outburst events.Broader Impacts of Proposed WorkThis project will enhance collaborations between physical oceanographers, paleoceanographers and paleoclimatologists. The Pacific Northwest Pleistocene floods are a phenomenon of great interest to the general public because they dramatically affected much of the regional landscape. Results of the proposed research will be used to educate the public about processes of current day climate change through connections to changes seen during glacial times. A young female post-doc will receive valuable cross-disciplinary training from three leading scientists in the geosciences.