Modeling the Role of Solar Variability in Late Pleistocene Millennial-Scale Climate Oscillations

这一奖项的目的是验证太阳变异性迫使热带气候变化在上一次冰川期间发生变化的假设。千禧年尺度的全新世太阳变率与北大西洋海冰漂移指标之间存在很强的相关性。之前的模拟研究表明，北大西洋地区不太可能迫使热带气候发生快速变化。相比之下，对上一次冰川的初步气候模拟表明，热带气候对太阳辐射的变化很敏感。据推测，太阳驱动的热带气候变化可能推动了热带外气候的快速振荡。这一假设的力量在于，它用已知的驱动力解释了热带和热带外冰川海洋的代理数据。该奖项将支持一系列晚更新世(海洋同位素阶段3)海-气-海-冰耦合实验，使用美国国家航空航天局的S古气候系统模型来验证这一假设。在建立了平衡控制实验后，将完成一系列由太阳辐照度合理变化所强制的分支运行。将对这些实验进行比较，并分析重要气候场的时间序列，以确定气候对太阳强迫的响应。由于热带水汽输送对冰川气候有潜在的重要作用，将利用社区大气模式(CAM)2.0的被动示踪能力来确定热带海洋水汽的路径和通量。为了确定热带和热带外区域之间的气候联系，将进行第二系列实验，将强制太阳强迫限于特定区域(例如热带)。这样，就有可能区分气候对太阳可变性的直接反应和由动力变化引起的间接反应。最后，模型结果将与现有的气候变化记录进行比较。这项研究应该对热带和热带外气候之间的联系提供有益的见解。

The objective of this award is to test the hypothesis that solar variability forced tropical climate change during the last glaciation. A strong correlation between millennial scale Holocene solar variability and North Atlantic sea-ice drift proxies has been found. Previous modeling studies indicate that the North Atlantic region is unlikely to force rapid tropical climate change. In contrast, a preliminary climate simulation of the last glaciation indicates that tropical climate is sensitive to changes in solar irradiance. It is hypothesized that solar-driven tropical climate change may have driven rapid extra-tropical climate oscillations. The strength of this hypothesis is that it explains both tropical and extra-tropical glacial marine proxy data with a known forcing. This award will support a series of late Pleistocene (Marine Isotope Stage 3) coupled ocean-atmosphere-sea-ice experiments using NCAR 's paleo-climate system model to test this hypothesis. After establishing an equilibrium control experiment, a series of branch runs forced by plausible changes in solar irradiance will be completed. The experiments will be compared and time series of important climate fields will be analyzed to identify the response of the climate to solar forcing. Because of the potentially important role for tropical water vapor transports to influence glacial climate, the passive tracer capabilities of Community Atmospheric Model (CAM) 2.0, will be implemented to determine the pathways and fluxes of water vapor from the tropical oceans. In order to identify climate linkages between tropical and extra-tropical regions, a second series of experiments will be conducted with the imposed solar forcing restricted to specific regions (e.g., the tropics). In this way, it will be possible to distinguish the direct climate response to solar variability from the indirect response resulting from dynamical changes. Finally, model results will be compared with existing records of climate change. This research should provide helpful insight into tropical - extra-tropical linkages in climate.