论文标题

数据驱动的2D Euler方程的随机谎言传输建模

Data-driven stochastic Lie transport modelling of the 2D Euler equations

论文作者

Ephrati, Sagy, Cifani, Paolo, Luesink, Erwin, Geurts, Bernard

论文摘要

在本文中,我们提出并评估了使用粗网格SPDE的二维Euler方程进行数据驱动的模型的几种随机参数化。谎言转运(盐)的随机对流框架[Cotter等,2019]被用来定义一种随机强迫,该强迫是根据确定性的基础(经验正交函数,EOFS)乘以时间痕迹的,此处被视为随机过程。 EOF是从细网格数据集获得的,并与相应的确定性时间序列结合定义。我们构建了模仿测得的时间序列的随机过程。特别地,定义了过程,以便保留了潜在的概率密度函数(PDF)或时间序列的估计相关时间。将这些随机模型与基于高斯噪声的随机强迫进行比较,而高斯噪声不使用时间序列的任何信息。我们执行不确定性定量测试,并根据平均值和扩散比较随机合奏。对于开发的模型观察到了降低的不确定性。在短时间内,例如用于数据同化的时间表[Cotter等,2020],随机模型显示出降低的集合平均误差和减少的扩展。特别是,使用估计的PDF产生随机集合,很少在较小的时间尺度上捕获参考解决方案,而将相关性引入随机模型会改善与高斯噪声相对于高斯噪声的粗网格预测的质量。

In this paper, we propose and assess several stochastic parametrizations for data-driven modelling of the two-dimensional Euler equations using coarse-grid SPDEs. The framework of Stochastic Advection by Lie Transport (SALT) [Cotter et al., 2019] is employed to define a stochastic forcing that is decomposed in terms of a deterministic basis (empirical orthogonal functions, EOFs) multiplied by temporal traces, here regarded as stochastic processes. The EOFs are obtained from a fine-grid data set and are defined in conjunction with corresponding deterministic time series. We construct stochastic processes that mimic properties of the measured time series. In particular, the processes are defined such that the underlying probability density functions (pdfs) or the estimated correlation time of the time series are retained. These stochastic models are compared to stochastic forcing based on Gaussian noise, which does not use any information of the time series. We perform uncertainty quantification tests and compare stochastic ensembles in terms of mean and spread. Reduced uncertainty is observed for the developed models. On short timescales, such as those used for data assimilation [Cotter et al., 2020], the stochastic models show a reduced ensemble mean error and a reduced spread. Particularly, using estimated pdfs yields stochastic ensembles which rarely fail to capture the reference solution on small time scales, whereas introducing correlation into the stochastic models improves the quality of the coarse-grid predictions with respect to Gaussian noise.

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