ECCE Seminar - The importance of dry intrusions for air-sea interaction and associated weather extremes

Dry intrusion (DI) air streams comprise the cold and dry sector of extratropical cyclones. These air parcels descend slantwise from the midlatitude upper troposphere towards the surface in lower latitudes, where the airstreams typically fan out behind the cyclone’s trailing cold front. Downward momentum transfer along DIs results in enhanced dry and cold surface winds and unstable boundary layers, all favouring intense air-sea interaction. In this talk I will review recent results based on a Lagrangian-based identification of DIs using representative case studies and longer-term climatologies, allowing the quantification of the intrusions’ occurrence frequencies and strong association with enhanced air-sea interaction. The key role of DIs in triggering intense air-sea interaction in the form of turbulent ocean heat and moisture loss provides new process-based insight on the DIs link to extreme weather events. Thus, DIs are not only directly related to strong winds and extreme cold temperatures but also to heavy precipitation ahead of the dry air. The importance of this link motivates the upcoming airborne field campaign NAWDIC, and extends from the midlatitudes to subtropical and tropical regions, opening new research avenues.