Temporal clustering of heavy precipitation events

Heavy precipitation has major societal and economic impacts which are not just tied to the intensity and frequency of these events at an aggregate level (e.g., seasonal and longer scales) but also in the way that they occur at a much finer temporal scale (e.g., daily). However, there is limited research examining whether these events occur in clusters, and what the physical drivers controlling their occurrences are. The nature of the arrival of these events has far reaching implications, from forecasting to ecology to the insurance/reinsurance sector.

Here I show that heavy precipitation events occur in bursts, with an alternating between quiet and active periods, with climate playing an important role in explaining this behavior. I focus on Europe and explore the role of four climate modes that have been found to play a major role in controlling the European weather and climate (Arctic Oscillation, North Atlantic Oscillation, Scandinavia Pattern, and East-Atlantic Pattern). I also expand my analyses to investigate the role of the El Niño-Southern Oscillation in controlling the occurrence of heavy precipitation events at the global scale.

I leverage the presence of temporal clustering to develop a new metric to assess whether climate models can reproduce the observed clustering behavior and the climate controls responsible for it. I show that climate models are skillful in reproducing this characteristic and they do so by capturing the right processes. Finally, I show that temporal clustering in heavy precipitation is expected to strengthen in response to an increase in greenhouse gasses.