Lagrangian pathways connecting the Weddell and Bellingshausen Seas

This study aims to assess the connectivity of currents around the Antarctic Peninsula and identify the structure of flows carrying particles from the Eastern to Western Antarctic Peninsula continental shelves. We use circulation data for the Weddell and Bellingshausen Seas from the “Whole Antarctica Ocean Model” to obtain and analyse particle trajectories using the “Probably A Really Computationally Efficient Lagrangian Simulator” (Parcels) model. In addition to the main Parcels kernels and a previously developed kernel that ensures the conservation of the number of particles during flow around irregularities in the bottom relief and the lower edge of ice shelves, we have also developed a kernel to simulate convection in the ocean upper mixed layer. Around 170,000 virtual particles were released at a depth of 10 m during a year with a spatial step of 1° in two shelf and slope sectors in the southern Weddell Sea where depth is less than 1500 m. The first sector covers a shelf area between 71°S and 77°S adjacent to the Filchner-Ronne Ice Shelf. The second sector covers a shelf area between 70°S and 65°S adjacent to the Larsen Ice Shelf.  The pathways of water masses were characterised by the visitation frequency (the percentage of particles P that visit each 10×10 km grid column at least once in a modelling period of 20 years). The proportion of particles crossing 58°W (tip of the Antarctic Peninsula) is 21% of the total amount, while the proportion of particles turning northeast is 70%.  The smaller sector, adjacent to the Larsen Ice Shelf, is the main source of particles transferred to the Bellingshausen Sea (51%). In contrast, particles released in the larger sector were mostly transported to the northeast (75%). Only 3.4% of the released particles were transported to the west of 80°W, while the Amundsen Sea (105°W) is reached only by 0.1% of released particles. This indicates a virtual lack of connectivity between the ocean circulation from the Weddell to the Amundsen Seas.