The cold transit of Southern Ocean upwelling

Evans, D. G. and Zika, J. D. and Naveira Garabato, A. C. and Nurser, A. J. G.

abstract: Deep, cold and salty water is drawn to the surface ocean aroundAntarctica. This is controlled by the combined action of winds blowing over the sea surface and the stirring by large 100-km eddies. Studying the ocean around Antarctica is notoriously challenging. We therefore have sparse ocean measurements in this region. This limits our understanding of some of the processes involved in the circulation of deep water, notably, a stage involving the warming and freshening of deep water to form intermediate water. Intermediate water plays a key role in drawing excess anthropogenic heat and carbon dioxide from the sea surface into the interior ocean. Our results show that the conversion of deep to intermediate water involves a two-stage ?cold transit? that takes place over the course of the austral season.First, during the winter, deep water sits below the very cold and fresh surface water. Ice formation aroundAntarctica makes this surface water slightly saltier, decreasing the density difference between the deep andsurface water. This drives a mixing which cools and freshens the deep water while drawing it to the surface.Second, during summer surface warming and melting sea ice warm and freshen this deep/surface watermixture forming intermediate water.

  author = {Evans, D. G. and Zika, J. D. and Naveira~Garabato, A. C. and Nurser, A. J. G.},
  journal = {grl},
  title = {The cold transit of {Southern Ocean} upwelling},
  year = {2018},
  pdfurl = {},
  doi = {10.1029/2018GL079986}