Mechanisms behind cyclone clustering

Cyclone clustering, the swift succession of extratropical cyclones in a short amount of time, has a huge impact on society. For example, it can lead to wind damage or excessive precipitation over longer periods of time at a particular location. However, cyclone clustering is not completely understood yet. On one side, extratropical cyclones grow by baroclinic instability (the large-scale temperature gradient), thereby reducing the large-scale baroclnicity. On the other side extratropical cyclones should also replenish this baroclinicity, to ensure that extratropical cyclones can keep on forming. One hypothesis could be that latent heating is important in re-establishing the temperature gradient.

In the PhD thesis of Thomas Batelaan, we will look in more detail on the mechanisms behind cyclone clustering. To test if latent plays a role in re-establishing the temperature gradient, he will perform idealised simulations of the February 2022 clustering case, which lead to damage in the UK and the Netherlands (see animation below). He uses the OpenIFS model in which the latent heating is shut off.

Clustering during February 2022 (mean sea level pressure indicated by black lines, and precipitation in mm/hour in shading)