History matching for exploring and reducing climate model parameter space using observations and a large perturbed physics ensemble
History matching for exploring and reducing climate model parameter space using observations and a large perturbed physics ensemble
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DOI：
10.1007/s00382-013-1896-4
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发表时间：
2013-08
期刊：
影响因子：
4.6
通讯作者：
D. Williamson;M. Goldstein;L. Allison;A. Blaker;P. Challenor;L. Jackson;K. Yamazaki
中科院分区：
文献类型：
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作者：
D. Williamson;M. Goldstein;L. Allison;A. Blaker;P. Challenor;L. Jackson;K. Yamazaki
我们应用一种已建立的称为历史匹配的统计方法来约束耦合的非通量调整气候模式(第三个Hadley中心气候模式；HadCM3)的参数空间，方法是使用一个10,000个成员的扰动物理集合和观测指标。历史匹配使用仿真器(气候模型的快速统计表示，在气候模型输出的预测中包括不确定性的测量)来排除气候模型的参数空间中与物理观测不一致的区域，因为存在相关的不确定性。我们的方法排除了气候模型大约一半的参数空间，即使我们只使用了少量的历史观测。我们探索了剩余空间的二维投影，并观察到一个区域的形状主要取决于控制云过程的参数和一个海洋混合参数。我们发现，全球平均地表温度(SAT)是所使用的约束的主要因素，其他因素在与SAT匹配后几乎没有进一步的约束。大西洋经向翻转环流(AMOC)与SAT具有非线性关系，在无约束参数空间中不能很好地反映经向热量输送，但在我们的简化空间中这些关系是线性的。我们发现，AMOC对每年1%和2%的理想化CO2强迫的瞬时响应在约束参数空间比在非约束空间显示出更大的平均强度衰减。我们测试了HadCM3的许多参数的扩展范围，并发现使用我们的任何约束都不能排除扩展范围的任何部分。在分析更复杂的过程之前，使用易于仿真的观测度量来约束参数空间是一个重要而强大的工具。它可以消除参数空间中不现实部分的复杂和不相关的行为，使所讨论的过程更容易被研究或模拟，或许可以作为应用进一步相关约束的先导。
We apply an established statistical methodology called history matching to constrain the parameter space of a coupled non-flux-adjusted climate model (the third Hadley Centre Climate Model; HadCM3) by using a 10,000-member perturbed physics ensemble and observational metrics. History matching uses emulators (fast statistical representations of climate models that include a measure of uncertainty in the prediction of climate model output) to rule out regions of the parameter space of the climate model that are inconsistent with physical observations given the relevant uncertainties. Our methods rule out about half of the parameter space of the climate model even though we only use a small number of historical observations. We explore 2 dimensional projections of the remaining space and observe a region whose shape mainly depends on parameters controlling cloud processes and one ocean mixing parameter. We find that global mean surface air temperature (SAT) is the dominant constraint of those used, and that the others provide little further constraint after matching to SAT. The Atlantic meridional overturning circulation (AMOC) has a non linear relationship with SAT and is not a good proxy for the meridional heat transport in the unconstrained parameter space, but these relationships are linear in our reduced space. We find that the transient response of the AMOC to idealised CO2forcing at 1 and 2 % per year shows a greater average reduction in strength in the constrained parameter space than in the unconstrained space. We test extended ranges of a number of parameters of HadCM3 and discover that no part of the extended ranges can by ruled out using any of our constraints. Constraining parameter space using easy to emulate observational metrics prior to analysis of more complex processes is an important and powerful tool. It can remove complex and irrelevant behaviour in unrealistic parts of parameter space, allowing the processes in question to be more easily studied or emulated, perhaps as a precursor to the application of further relevant constraints.