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A comprehensive model for the kyr and Myr timescales of Earth's axial magnetic dipole field
Nonlinear Processes in Geophysics ( IF 2.2 ) Pub Date : 2019-07-08 , DOI: 10.5194/npg-26-123-2019
Matthias Morzfeld , Bruce A. Buffett

Abstract. We consider a stochastic differential equation model for Earth's axial magnetic dipole field. Our goal is to estimate the model's parameters using diverse and independent data sources that had previously been treated separately, so that the model is a valid representation of an expanded paleomagnetic record on kyr to Myr timescales. We formulate the estimation problem within the Bayesian framework and define a feature-based posterior distribution that describes probabilities of model parameters given a set of features derived from the data. Numerically, we use Markov chain Monte Carlo (MCMC) to obtain a sample-based representation of the posterior distribution. The Bayesian problem formulation and its MCMC solution allow us to study the model's limitations and remaining posterior uncertainties. Another important aspect of our overall approach is that it reveals inconsistencies between model and data or within the various data sets. Identifying these shortcomings is a first and necessary step towards building more sophisticated models or towards resolving inconsistencies within the data. The stochastic model we derive represents selected aspects of the long-term behavior of the geomagnetic dipole field with limitations and errors that are well defined. We believe that such a model is useful (besides its limitations) for hypothesis testing and give a few examples of how the model can be used in this context.

中文翻译:

地球轴向磁偶极子场 kyr 和 Myr 时间尺度的综合模型

摘要。我们考虑地球轴向磁偶极子场的随机微分方程模型。我们的目标是使用先前单独处理的不同且独立的数据源来估计模型的参数,以便该模型是 kyr 到 Myr 时间尺度上扩展的古地磁记录的有效表示。我们在贝叶斯框架内制定了估计问题,并定义了一个基于特征的后验分布,该分布描述了给定一组从数据派生的特征的模型参数的概率。在数值上,我们使用马尔可夫链蒙特卡罗 (MCMC) 来获得基于样本的后验分布表示。贝叶斯问题公式及其 MCMC 解决方案使我们能够研究模型的局限性和剩余的后验不确定性。我们整体方法的另一个重要方面是它揭示了模型和数据之间或各种数据集内的不一致。识别这些缺点是构建更复杂模型或解决数据不一致的第一步,也是必要的一步。我们推导出的随机模型代表了地磁偶极场长期行为的选定方面,具有明确定义的局限性和误差。我们相信这样的模型对于假设检验是有用的(除了它的局限性),并给出了一些关于如何在这种情况下使用模型的例子。识别这些缺点是构建更复杂模型或解决数据不一致的第一步,也是必要的一步。我们推导出的随机模型代表了地磁偶极场长期行为的选定方面,具有明确定义的局限性和误差。我们相信这样的模型对于假设检验是有用的(除了它的局限性),并给出了一些关于如何在这种情况下使用模型的例子。识别这些缺点是构建更复杂模型或解决数据不一致的第一步,也是必要的一步。我们推导出的随机模型代表了地磁偶极场长期行为的选定方面,具有明确定义的局限性和误差。我们相信这样的模型对于假设检验是有用的(除了它的局限性),并给出了一些关于如何在这种情况下使用模型的例子。
更新日期:2019-07-08
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