Storm tracks and cyclogenesis over the Southern Ocean: An overview with the HadGEM3-GC3.1 model

Abstract

Abstract Wide areas of the globe have their weather and climate strongly influenced by the action of extratropical cyclones. However, the characteristics of cyclones, their formation, displacement, and dissipation areas are dependent on the data and methodology employed. Here, we have evaluated the characteristics and spatial distribution of extratropical cyclones that had their genesis in the Southern Ocean (SO) in the present climate, based on data from the HadGEM3-GC3.1-MM (HG3) global model and the ERA5 reanalysis. Both in winter and in summer, cyclone tracks are spatially structured, forming a belt around the entire Antarctic continent, with greater concentration in the SO sector adjacent to the southern Pacific Ocean. Moderate and strong cyclones presented their trajectories in greater density in the regions of the Bellingshausen, Amundsen, and Somov seas, suggesting a correlation with the highest baroclinity in these regions. In both datasets, the maximum occurrence of cyclogenesis was located over the regions of the Somov Sea and the Antarctic Peninsula, making these regions very important in the general configuration of cyclones along the SO. Despite underestimating the total number of cyclones along the SO, the HG3 model showed a good ability to represent the main patterns of cyclonic activity around the Antarctic continent, as well as its average behavior. Knowing the characteristics and the behavior of extratropical cyclones in such an important area for global climate is essential for understanding their role in weather and future climate resulting from climate change.