North Atlantic SST variability during strong winter extratropical cyclones

Extreme weather and climate events, such as extratropical cyclones and droughts, represent a topic of paramount importance in the Iberian Peninsula and the North Atlantic Ocean plays an important role in shaping their frequency and intensity. Sea surface temperature (SST) variations, which are important indicators of ocean variability, can result in anomalous diabatic heating or cooling of the overlying atmosphere. In this study, the contributions of different physical processes to the development of North Atlantic explosive extratropical cyclones (EC) affecting the Iberian Peninsula are investigated using the ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF). Results suggest that the North Atlantic Ocean SST contributed to the formation and intensification of extratropical cyclones, and particularly to the formation and development of intense storms. Furthermore, the combined analysis of SST and net surface heat flux (QN) also shows the cooling of the ocean associated with the EC tracks caused by the heat exchanges between the ocean and the atmosphere. Acknowledgements This work is supported by national funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020 (https://doi.org/10.54499/UIDB/04033/2020).