Collaborative Research: An Inverse Model Study of Abrupt Climate Change

在这一奖项下，PIS将使用在最优控制理论和贝叶斯随机反演框架内开发的数据同化技术，将格陵兰古温度记录与大西洋海洋-大气系统的数值模式(相对简单的盒子模式和较复杂的Stocker/Wright纬向平均模式)结合在一起。PI希望估计海洋同位素阶段3(24.1-59.0ka BP)期间大西洋MOC、Fh和表层淡水强迫的时间演变，这与格陵兰的记录和模型中包含的物理特性都是一致的。估计的演化与大西洋沉积物的古海洋学记录相结合，将被用来评估该理论解释快速气候变化的充分性。古气候记录，特别是来自北大西洋地区的记录，记录了最后一次冰川期间的一系列暖期，通常被称为丹斯加德-奥施格间期(DOI)。格陵兰冰中记录的DOI的开始对应着在几十年内发生的极大的温度跃升(7-16摄氏度)。DOIS的发现表明，气候系统向一种新的气候状态的突变是动态可能的。了解DOI的起源是评估未来“意外”转变的可能性的重要部分。一个主要的突变理论提出了大西洋经向翻转环流(MOC)和纬向和深度积分热通量(Fh)对北半球冰盖冰川融水排放的敏感性。

Under this award the PIs will use data assimilation techniques developed in the framework of optimal control theory and Bayesian stochastic inversion, to combine the Greenland paleotemperature record and numerical models of the ocean-atmosphere system in the Atlantic (a relatively simple box model and the more complex Stocker/Wright zonally-averaged model). The PIs hope to estimate the temporal evolutions of the Atlantic MOC, Fh, and surface freshwater forcing during the marine isotope stage 3 (24.1-59.0 ka BP) that are consistent with both the Greenland record and the physics embedded in the models. The estimated evolutions, in concert with paleoceanography records from Atlantic sediments, will be used to assess the adequacy of the theory to explain rapid climate change. Paleoclimate records, in particular those from the North Atlantic area, document a series of warm phases during the last glaciation, commonly referred to as Dansgaard-Oeschger interstadials (DOI). The onsets of DOIs recorded in Greenland ice corresponded to extremely large temperature jumps (7-16oC) that occurred within a span of a few decades. The discovery of DOIs demonstrates that it is dynamically possible for the climate system to make an abrupt transition to a new climate state. Understanding the origin of DOIs is an important part of assessing the possibility for future 'surprise' transitions. A leading theory of abrupt change invokes the susceptibility of the meridional overturning circulation (MOC) and zonally- and depth-integrated heat flux (Fh) in the Atlantic, to glacial meltwater discharges from northern hemisphere ice sheets.