Internal and External Causes of Climatic Changes

摘要ATM-9523787 Ghil，Michael加州大学，洛杉矶题目：气候变化的内部和外部原因 PI将研究气候的三个一般领域： 1.他将继续研究第四纪冰川的物理机制。 这些机制的简单和中间模型将进一步发展，包括零，一，二，三维模型的古海洋温盐环流（THC），除了以前模拟的辐射平衡，冰盖质量平衡，水文循环。 模型结果将在光谱和时间域与海洋，冰芯和大陆记录进行比较，强调与海洋Heinrich和冰芯Dansgaard- Oeschger事件及其空间模式相关的快速变化。 2.对大气低频变率的研究，重点是中纬度大气的季节内振荡，已通过一系列简单和中等模式的理论研究、最长高空数据集的观测研究以及使用加州大学洛杉矶分校大气环流模式的研究进行。 PI应通过直接比较中间模型、GCM和观测分析结果来完成本研究。 正压气流在地形上的实验室研究也应该进一步阐明振荡的物理机制。 3.年代际时间尺度上的自然气候变率是第三个新的研究领域。 初步，单变量的研究仪器记录将扩展到探索这种变异的空间格局。 二维和三维THC模型将与主动和被动大气和海冰模型相结合。 将首先研究这些模式的恒定辐射强迫，然后研究由于太阳变化、火山爆发和温室气体增加而导致这种强迫发生变化的不同情景。 这些长周期的、间歇性的或逐渐的变化与短周期的年周期引起的变化之间的相互作用将被仔细地研究。 调查的所有三个重点都旨在澄清气候系统的自然变率--季节内、年代际或千年--和变量强迫之间的相互作用：在季节内情况下是大气外部，在其他两种情况下是整个气候系统。 所使用的工具是动力系统理论，模型研究，和非参数统计，模型诊断和数据分析。 最终，拟议的研究应该提高我们对影响或限制系统在三个时间尺度上的可预测性的因素的理解。

Abstract ATM-9523787 Ghil, Michael University of California, Los Angeles Title: Internal and External Causes of Climatic Changes The PI will study three general areas of climate: 1. He will continue research on the physical mechanisms of Quaternary glaciations. Simple and intermediate models of these mechanisms will be developed further, including zero-, one-, two- and three dimensional models of the paleoceanic thermohaline circulation (THC), in addition to the previously-modeled radiation balance, ice-sheet mass balance, and hydrologic cycle. Model results will be compared in the spectral and temporal domain with marine, ice-core and continental records, emphasizing rapid variations associated with marine Heinrich and ice-core Dansgaard- Oeschger events, and their spatial patterns. 2. Research on the low-frequency variability of the atmosphere, emphasizing intraseasonal oscillations in the midlatitude atmosphere, has proceeded through theoretical studies with a hierarchy of simple and intermediate models, observational studies of the longest upper-air datasets, and studies using the UCLA general circulation model. The PI shall complete this research with a direct comparison of intermediate-model, GCM, and observational-analysis results. A laboratory study of barotropic flow over topography should also shed further light on the oscillations' physical mechanisms. 3. Natural climate variability on the interdecadal time scale is the third, and new area of research. Preliminary, univariate studies of instrumental records will be extended to explore this variability's spatial patterns. Two- and three-dimensional THC models will be coupled with active and passive atmospheric and sea- ice models. These models will be studied first for constant radiative forcing and then for different scenarios of changes in this forcing, due to solar variability, volcanic eruptions and greenhouse-gas increases. The interaction of these long-periodic, intermittent or g radual changes with those caused by the short- periodic annual cycle will be examined carefully. All three thrusts of the investigation are aimed at clarifying the interaction between the climatic system's natural variability - intraseasonal, interdecadal or millennial - and the variable forcing: external to the atmosphere, in the intraseasonal case, and to the climate system as a whole, in the other two. The tools to be used are those of dynamical systems theory, for the model studies, and of nonparametric statistics, for the model diagnostics and data analysis. Ultimately, the proposed research should improve our understanding of the factors that contribute to or limit the system's predictability on each one of the three time scales under consideration.