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Abstract:
In February 2022, a cluster of severe extratropical cyclones hit North-Western Europe within one week and caused widespread damage by wind gusts and accumulated precipitation. In that week, extratropical cyclones Dudley, Eunice and Franklin developed over the North-Atlantic within a baroclinic environment with strong jet streams accompanied with atmospheric rivers. We hypothesise that diabatic heating through latent heat release within the extratropical cyclones created a baroclinic environment favourable for secondary cyclogenesis. We presume that latent heating on the trailing cold-front of the primary cyclone was essential for the secondary cyclogenesis. To identify the influence of latent heat release on the cyclogenesis of these storms, we performed idealised simulations with the Open Integrated Forecast System (OpenIFS). Latent heat of vaporisation was doubled, switched off and reduced with a factor of hundred.
The control run captured the individual cyclones, their intensities and path reasonably well; OpenIFS is suitable to fulfil our objectives. First results showed that reduced latent heating negatively impacted the cyclogenesis of secondary cyclone Eunice — the severest extratropical cyclone during that week. Overall, the baroclinicity was strongly weakened over the North-Atlantic. Furthermore, we plan experiments that examine the importance of latent heat release along the cold-front of the primary cyclone by only reducing latent heat in a box along the trailing cold-front. With this case-study we explore diabatic heating as a pathway for cyclone clustering.
