Ph.D. Program in Oceanography and Global Change at the Canary Islands, Spain
We analyze the Bransfield Current (BC), which is a relatively warm baroclinic jet (0-250 m) flowing northeastward at the Bransfield Strait (BS) and along the southern slope of the South Shetland Islands (SSI) in the west Antarctic Peninsula. Recent studies have shown that the BC propagates as a buoyant gravity current, recirculating around the north-eastern tip of the islands while shedding an anticyclonic eddy. However, most previous works are based on summertime hydrographic measurements and surface drifters and, therefore, a more comprehensive spatio-temporal view of the regional circulation is still lacking to further understand the governing shelf dynamics.
In this study we provide the first year-round description of the Bransfield Current based on an extensive dataset of direct velocity measurements. These measurements were routinely collected along ship tracks from 375 cruises between 1999 and 2014. From these observations, a novel climatological characterisation has been developed to examine the seasonal variability of the BC.
Results support the BC is a recurrent feature of the circulation in Bransfield Strait, flowing northeastward all along the southern slope of the SSI not only during summer (up to 40 cm/s) but also during spring and autumn at velocities up to 30 and 20 cm/s, respectively. We note that winter data scarcity prevents us from a similar statement during this season but still enables the confirmation of a strong northeastward-flowing current at least south off Nelson Island with velocities about 15 cm/s. Lastly, the recirculation of the BC around the northeasternmost tip of the SSI also appears apparent in all seasons but during summer.
