Spatial Extremes: Zhongwei Zhang
From Belle Taylor on July 5th, 2021
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Name: Zhongwei Zhang
Talk Title: Modeling Spatial Extremes Using Normal Mean-Variance Mixtures
Abstract: Classical models for multivariate or spatial extremes are mainly based upon the asymptotically justified max-stable or generalized Pareto processes. These models are suitable when asymptotic dependence is present, i.e., the joint tail decays at the same rate as the marginal tail. However, recent environmental data applications suggest that asymptotic independence is equally important and, unfortunately, existing spatial models in this setting that are both flexible and can be fitted efficiently are scarce. Here, we propose another copula model based on the generalized hyperbolic distribution, which is a specific normal mean-variance mixture and is very popular in financial modeling. The tail properties of this distribution have been studied in the literature, but with contradictory results. It turns out that the proofs from the literature contain mistakes. We here give a corrected theoretical description of its tail dependence structure and then exploit the model to analyze the hindcast significant wave height data considered in Wadsworth & Tawn (2012) and Huser & Wadsworth (2019), and wind gust data in the state of Oklahoma, USA. We demonstrate that our proposed model is flexible enough to capture the dependence structure not only in the tail but also in the bulk.
This talk is a contributed talk at EVA 2021.