We are delighted to announce the winner of the Wiley-TIES best paper award for 2024. The award has been given to the article:
, & (2024). Elastic functional changepoint detection of climate impacts from localized sources. Environmetrics, 35(1), e2826. https://doi.org/10.1002/env.2826
The paper develops a novel and computationally efficient elastic functional change point detection approach, which relies on the amplitude-phase decomposition of the functional variability. It is grounded in functional data analysis and differs substantially from other traditional change-point detection methods. The new approach has a broad range of environmental applications, as demonstrated in the paper with an analysis of stratospheric temperature, in which the authors’ method was able to successfully detect changes in the tropics after the eruption of Mt Pinatubo. The winning paper thus provides a significant contribution to the field of environmetrics.
Abstract
Detecting changepoints in functional data has become an important problem as interest in monitoring of climate phenomenon has increased, where the data is functional in nature. The observed data often contains both amplitude (y-axis) and phase (x-axis) variability. If not accounted for properly, true changepoints may be undetected, and the estimated underlying mean change functions will be incorrect. In this article, an elastic functional changepoint method is developed which properly accounts for these types of variability. The method can detect amplitude and phase changepoints which current methods in the literature do not, as they focus solely on the amplitude changepoint. This method can easily be implemented using the functions directly or can be computed via functional principal component analysis to ease the computational burden. We apply the method and its nonelastic competitors to both simulated data and observed data to show its efficiency in handling data with phase variation with both amplitude and phase changepoints. We use the method to evaluate potential changes in stratospheric temperature due to the eruption of Mt. Pinatubo in the Philippines in June 1991. Using an epidemic changepoint model, we find evidence of a increase in stratospheric temperature during a period that contains the immediate aftermath of Mt. Pinatubo, with most detected changepoints occurring in the tropics as expected.