Hierarchical space-time modeling of asymptotically independent exceedances for hourly precipitations in southern France

International audience; The statistical modeling of space-time extremes in environmental applications is key to understanding complex dependence structures in original event data and to generating realistic scenarios for impact models. In this context of high-dimensional data, we propose a novel hierarchical model for high threshold exceedances defined over continuous space and time by embedding a space-time Gamma process convolution for the rate of an exponential variable, leading to asymptotic independence inspace and time. Its physically motivated anisotropic dependence structure is based on geometric objects moving through space-time according to a velocity vector. We demonstrate that inference based on weighted pairwise likelihood is fast and accurate. The usefulness of our model is illustrated by an application to hourly precipitation data from a study region in Southern France, where it clearly improves on an alternative censored Gaussian space-time random field model. While classical limit models based on threshold-stability fail to appropriately capture relatively fast joint tail decay1arXiv:1708.02447v2 [stat.ME] 14 May 2019rates between asymptotic dependence and classical independence, strong empirical evidence from ourapplication and other recent case studies motivates the use of more realistic asymptotic independencemodels such as our