By Mike Meredith

Science on the British Antarctic Survey’s research vessel RRS Sir David Attenborough cruise SD050 has now entered full swing, with sequences of oceanographic measurements close to the Sheldon Glacier near Rothera, near Blaiklock Island, and adjacent to the Horton and Hurley Glaciers. This cruise is a rare wintertime expedition with the ship, and affords us an excellent opportunity to further our understanding of how glaciers impact the ocean, and vice versa. It contributes to a number of scientific projects, including serving as a precursor the main POLOMINTS fieldwork that starts next season.

During our transit south to Rothera, we took the opportunity to make measurements in some important field sites along the way, including Börgen Bay on Anvers Island. This was the location where we witnessed a major glacier calving event some years ago, with bursts of rapid and intense ocean mixing as a result – the occurrence that led to the POLOMINTS project. We were surprised to again witness a calving event in Börgen Bay, albeit a smaller one, since such calvings are much more frequent in summer. We’ll be examining the data we collected there closely to look for the impacts on the ocean, and to better understand the seasonal differences in such effects.

One of the main instruments we are using on this cruise is a Conductivity-Temperature-Depth (CTD) system, which is lowered from the ship to near the seabed, and which provides us with vertical profiles of key ocean variables that we’re interested in: temperature, salinity, chlorophyll concentration, and so on. We’re also collecting water samples for analysis in the ship’s laboratories, with some being saved for analysis back in the UK, and additionally will be collecting sediment samples. Taken together, these data and samples will help progress our understanding of how glacier melt and calving affects the ocean, and how nutrients fuel the growth of life in the sea. Ultimately, the science will contribute to our understanding of how the ocean around Antarctica impacts climate and the ecosystem, with the wintertime nature of these data will making them especially valuable.

We are most grateful to the outstanding work of the officers and crew of RRS Sir David Attenborough for supporting this science !