Seasonal and Interannual Variability of the Weddell Gyre From a High-Resolution Global Ocean-Sea Ice Simulation During 1958–2018

The Weddell Gyre's variability on seasonal and interannual timescales is investigated using an ocean-sea ice model at three different horizontal resolutions. The model is evaluated against available observations to demonstrate that the highest resolution configuration (0. (Formula presented.) in the horizontal) best reproduces observed features of the region. The simulations suggest that the gyre is subject to large variability in its circulation that is not captured by summer-biased or short-term observations. The Weddell Gyre's seasonal cycle consists of a summer minimum and a winter maximum and accounts for changes that are between one third and a half of its mean transport. On interannual time scales we find that the gyre's strength is correlated with the local Antarctic easterlies and that extreme events of gyre circulation are associated with changes in the characteristics of the warm inflow at the eastern boundary, that in turn drives changes in sea ice concentration.