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arXiv 2208.03344stat.MEstat.AP
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利用深度学习近似与灵活空间过程对极端径流建模

Modeling Extremal Streamflow using Deep Learning Approximations and a Flexible Spatial Process

Reetam Majumder, Brian J. Reich, Benjamin A. Shaby

AI总结:

本文提出过程混合模型结合神经网络密度回归与Vecchia近似,解决空间极值建模中似然不可处理的问题,并用于分析美国50年年最大径流变化,识别极端径流增加区域。

摘要:

量化极端洪水事件发生概率和强度的变化是减轻其影响的关键。虽然水文数据本质上具有空间依赖性,但高斯过程等传统空间模型并不适合对极端事件建模。具有更真实尾部依赖特征的空间极值模型正在积极发展中。这些模型在理论上有依据,但其似然函数难以处理,使得小数据集的计算具有挑战性,而在大陆尺度研究中则不可行。我们提出一种过程混合模型(PMM),将极端值的空间依赖指定为高斯过程与最大稳定过程的凸组合,从而获得理想的尾部依赖性质,但似然函数难以处理。为解决这一问题,我们采用一种独特的计算策略:将前馈神经网络嵌入密度回归模型中,以近似给定一组邻域时某一空间位置的条件分布。然后,我们利用这一单变量密度函数,通过Vecchia近似来逼近所有位置的联合似然。该PMM用于分析美国过去50年年最大径流的变化,并能够识别出随时间呈现极端径流增加的区域。

英文摘要:

Quantifying changes in the probability and magnitude of extreme flooding events is key to mitigating their impacts. While hydrodynamic data are inherently spatially dependent, traditional spatial models such as Gaussian processes are poorly suited for modeling extreme events. Spatial extreme value models with more realistic tail dependence characteristics are under active development. They are theoretically justified, but give intractable likelihoods, making computation challenging for small datasets and prohibitive for continental-scale studies. We propose a process mixture model (PMM) which specifies spatial dependence in extreme values as a convex combination of a Gaussian process and a max-stable process, yielding desirable tail dependence properties but intractable likelihoods. To address this, we employ a unique computational strategy where a feed-forward neural network is embedded in a density regression model to approximate the conditional distribution at one spatial location given a set of neighbors. We then use this univariate density function to approximate the joint likelihood for all locations by way of a Vecchia approximation. The PMM is used to analyze changes in annual maximum streamflow within the US over the last 50 years, and is able to detect areas which show increases in extreme streamflow over time.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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