Internal and External Causes of Climatic Changes

题目：气候变化的内因和外因PI将研究气候的三个一般领域：1.气候变化的内因和外因；他将继续研究第四纪冰川作用的物理机制。这些机制的简单和中间模型将进一步发展，包括古海洋热盐环流（THC）的零、一维、二维和三维模型，以及先前模拟的辐射平衡、冰盖质量平衡和水文循环。模式结果将在光谱和时域与海洋、冰芯和大陆记录进行比较，强调与海洋Heinrich和冰芯Dansgaard- Oeschger事件及其空间格局相关的快速变化。2. 关于大气低频变率的研究，重点是中纬度大气的季节内振荡，已经通过基于简单和中间模式的理论研究、基于最长高空数据集的观测研究和基于UCLA环流模式的研究进行了。PI将通过直接比较中间模型、GCM和观测分析结果来完成这项研究。对地形正压流的实验室研究也将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。初步的单变量仪器记录研究将扩展到探索这种变异性的空间模式。二维和三维THC模型将与主动和被动大气和海冰模型耦合。这些模式将首先研究恒定的辐射强迫，然后研究由于太阳变率、火山爆发和温室气体增加而导致的这种强迫变化的不同情景。这些长周期、间歇或渐进变化与短周期年循环引起的变化之间的相互作用将被仔细研究。调查的所有三个重点都是为了澄清气候系统的自然变率- -季节内、年代际或千年- -和可变强迫之间的相互作用：在季节内的情况下是大气外的强迫，在其他两种情况下是整个气候系统的强迫。要使用的工具是用于模型研究的动力系统理论工具，以及用于模型诊断和数据分析的非参数统计工具。最终，拟议的研究应该提高我们对促成或限制系统在考虑的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.