CIRCULATION IN THE ROSS SEA SECTOR OF THE SOUTHERN OCEAN: REPRESENTATION IN NUMERICAL MODELS

The circulation in the Ross Sea sector of the Southern Ocean is examined in three numberical models of intermediate to high resolution. Despite the model differences (including physics, forcing) the circulation representation is relatively consistent, both in terms of the mean and some aspects of monthly variability. This could point to strong bathymetric constraints on the circulation. In particular, the models sugges a pair of cyclonic gyres separated by shallow bathymetry around 180º E that redistribute water from the wider Southern Ocean into and out of the Ross Sea. The southermost gyre boundaries comprise the Antarctic Shelf Front and the Antarctic Coastal Current. To the north the gyres are bounded by the Antarctic Circumpolar Current. The model solutions also suggest that as the model Antarctic Circumpolar Current transport reduces, the gyral transport within the Ross Sea increases. Model flows at around 900 metres compare favourably with float data. Further, model depth-averaged flow on the Ross Sea shelf is relatively consistent with that reconstructed from longline fishing records.