Modelling time series with multiple seasonalities: an application to hourly NO\({_2}\) pollution levels
摘要
Multiple seasonalities often appear in high-frequency data such as hourly measurements of air pollutants. These multiple seasonalities are due to human activities, with daily and weekly cycles, and climatic conditions, with daily and annual cycles. Multiple seasonal components were in the past often modelled in a deterministic way by trigonometric functions or dummy variables. Since pollution seasonalities vary over time, the deterministic assumption is very strict and a more flexible model is needed. We propose to allow seasonality to slowly change as a seasonal autoregressive integrated moving average (ARIMA) model, where the seasonality is modelled as a stochastic process (combining different seasonal ARIMA models). We apply the proposed methodology to