Non-Stationary Large-Scale Statistics of Precipitation Extremes in Central Europe

TL;DR

This paper introduces a flexible model for analyzing non-stationary extreme precipitation in Central Europe, incorporating large-scale climate variables and providing improved predictions and insights into climate effects on extremes.

Contribution

The study develops a novel generalized extreme value model that integrates large-scale climate indices and uses aggregated maxima for multi-scale analysis, outperforming traditional models.

Findings

Extreme precipitation probability increased since 1950 across seasons.

Blocking patterns and temperature significantly influence extreme precipitation.

Model outperforms reference models lacking large-scale variable integration.

Abstract

Extreme precipitation shows non-stationary behavior over time, but also with respect to other large-scale variables. While this effect is often neglected, we propose a model including the influence of North Atlantic Oscillation, time, surface temperature and a blocking index. The model features flexibility to use annual maxima as well as seasonal maxima to be fitted in a generalized extreme value setting. To further increase the efficiency of data usage maxima from different accumulation durations are aggregated so that information for extremes on different time scales can be provided. Our model is trained to individual station data with temporal resolutions ranging from one minute to one day across Germany. The models are selected with a stepwise BIC model selection and verified with a cross-validated quantile skill index. The verification shows that the new model performs better than a reference model without large scale information. Also, the new model enables insights into the effect of large scale variables on extreme precipitation. Results suggest that the probability of extreme precipitation increases with time since 1950 in all seasons. High probabilities of extremes are positively correlated with blocking situations in summer and with temperature in winter. However, they are negatively correlated with blocking situations in winter and temperature in summer.