A Cold Frontal Life Cycle Climatology and Front-Cyclone Relationships over the North Atlantic and Europe during Winter

Atmospheric fronts and cyclones play an important role in day-to-day weather variability, especially in the mid-latitudes and during the winter season. Severe rainfall and windstorm events are often associated with the passage of a front or a cyclone. While there are many studies of individual fronts and climatologies based on objectively detected fronts, there is no comprehensive study considering the whole frontal life cycle over time. Therefore, a front and cyclone tracking algorithm, based on overlapping features at consecutive time steps, is used together with an improved front detection method to detect and track cold fronts and cyclones over the North Atlantic and Europe in the extended winter season (October - March) in the ERA5 reanalysis dataset. Several life cycle characteristics, e.g. the duration, velocity, frontogenesis and -lysis regions as well as dynamic and thermodynamic frontal parameters are defined to investigate the frontal life cycle and the conditions and processes in the frontal region. Fronts are linked to their parent cyclone to study relationships between frontal and cyclonic properties. The study confirms that fronts are mostly formed over the western and central North Atlantic and travelling along the main storm track into the European continent. During positive phases of the North Atlantic Oscillation, fronts are travelling faster and further and are associated with stronger precipitation and surface wind speeds over their whole life cycle. Stronger cyclones are related to stronger dynamics in the frontal region.