Nonstationary POT modelling of air pollution concentrations: Statistical analysis of the traffic and meteorological impact

作者：Gyarmati Szabo Janos; Bogachev Leonid V^*; Chen Haibo

来源：Environmetrics, 2017, 28(5): e2449.

DOI：10.1002/env.2449

• extreme values
• generalized Pareto distribution (GPD)
• nonstationarity
• peaks-over-threshold (POT)
• roadside air pollution
• threshold stability

Predicting the occurrence, level, and duration of high air pollution concentrations exceeding a given critical level enables researchers to study the health impact of road traffic on local air quality and to inform public policy action. Precise estimates of the probabilities of occurrence and level of extreme concentrations are formidable due to the combination of complex physical and chemical processes involved. This underpins the need for developing sophisticated extreme value models, in particular allowing for nonstationarity of environmental time series. In this paper, extremes of nitrogen oxide (NO), nitrogen dioxide (NO2), and ozone (O-3) concentrations are investigated using two models. ModelI is based on an extended peaks-over-threshold (POT) approach developed by A. C. Davison and R. L. Smith, whereby the parameters of the underlying generalized Pareto distribution (GPD) are treated as functions of covariates (i.e., traffic and meteorological factors). The new ModelII resolves the lack of threshold stability in the Davison-Smith model by constructing a special functional form for the GPD parameters. For each of the models, the effects of traffic and meteorological factors on the frequency and size of extreme values are estimated using Markov chain Monte Carlo methods. Finally, appropriate goodness-of-fit tests and model selection criteria confirm that ModelII significantly outperforms ModelI in estimation and forecasting of extremes.

• 出版日期2017-8