Concentrations of dissolved and atmospheric nitrous oxide, N2O, were measured in the austral spring of 1992 in the Drake Passage and Bellingshausen Sea as part of the United Kingdom Joint Global Ocean Flux Study expedition to the Southern Ocean. The measured atmospheric mixing ratio was 313 +/- 5 parts per billion by volume, in agreement with the hemispherically corrected global mean. In the Drake Passage, surface N2O saturations were generally very close to atmospheric equilibrium, 99.7 +/- 3%, although several anomalous points were associated with the presence of frontal and eddy-like features within the Antarctic Polar Frontal Zone and at the Continental Water Boundary. Further to the south, a series of oceanographic stations and two surface transects along the 85 degrees W meridian between 65.28 degrees S and 70.32 degrees S revealed a transition from undersaturated conditions in open water to oversaturated conditions in the marginal ice zone, in the upper mixed layer (75-100 m). These observations reflect upwelling of Circumpolar Deep Water at approximately 70 degrees S, resulting in the accumulation of N2O under the winter sea ice and its subsequent release to the atmosphere following the ice retreat. Sea-air N2O fluxes were estimated from the product of the surface N2O anomaly and the modelled gas transfer coefficients of Liss and Merlivat [1986] and Wanninkhof [1992] to find a maximum rate of +3.1 micromole N2O m-2 d -1. North of the upwelling region, Antarctic Surface Water formed from the mixing of surface waters and ice melt was moderately depleted in N2O with respect to the atmosphere, a minimum 90% of saturation. This sink area was estimated to extend between 65.28 degrees S and 69.57 degrees S with a mean sea-air flux of between -0.6 +/- 0.4 and -0.9 +/- 0.7 micromole N2O m-2 d-1. The region studied at 85 degrees W (65.28 degrees S to 70.32 degrees S) revealed source and sink areas which were largely determined by the changing physical hydrography, so that overall there was a small net negative flux of between -0.06 +/- 0.9 and -0.09 +/- 1.4 micromole N2O m-2 d-1. Funding: The work was supported by NERC funding to the Plymouth Marine Laboratory, the British Antarctic Survey and from the U.K. Biogeochemical Flux Study (BOFS).

Acoustic backscatter data were collected on board the RRS James Clark Ross (cruise JR179) as part of the BIOFLAME-BIOPEARL programme. Data were collected using a Simrad EK60 echo sounder. Data were collected throughout the cruise which ran through the Drake Passage, Bellingshausen Sea and Amundsen Sea in the Southern Ocean, from February to April 2008. The raw data files (Simrad .raw format) are held by the Polar Data Centre (PDC) at the British Antarctic Survey (BAS). *******PLEASE BE ADVISED TO USE PROCESSED DATA******* The JR179 EK60 processed data is now available at https://doi.org/10.5285/ecc51062-1338-445e-bd3c-2e63487d1953.

We present here Topographic Parametric Sonar (TOPAS) acoustic sub-bottom profiler data acquired on RRS James Clark Ross JR298 cruise in 2015. Data are provided in SEG-Y format. This project was funded by UK Natural Environment Research Council Grant NE/J006548/1: Depositional patterns and records in sediment drifts off the Antarctic Peninsula and West Antarctica

This dataset contains sea-air methane flux data from January 2019 to March 2021 measured using a Picarro G2311-f greenhouse gas analyser onboard RRS James Clark Ross, in the Southern Ocean, Arctic Ocean and Atlantic Ocean. The fluxes are 2 hour averaged and have been filtered based on wind direction to data corresponding to wind coming from behind the ship to remove sources of pollution from the ship stack. Limit of detection for the flux data are calculated for each cruise by multiplying the standard deviation of the random noise by three. This work was supported by the Natural Environment Research Council and the ARIES Doctoral Training Partnership (grant no. NE/S007334/1). Royal Holloway, University of London was funded by NERC through grants NE/V000780/1 and NE/N016211/1. Anna E. Jones and Katrin Linse were part of the British Antarctic Survey Polar Science for Planet Earth Programme funded by the Natural Environment Research Council (NERC) [NC-Science]. The measurements from the Royal Research Ship James Clark Ross (JCR) were principally supported by the UK Natural Environment Research Council's ORCHESTRA project (Grant No. NE/N018095/1). The Picarro analyser was funded by the European Space Agency funding (ESA AMT4OceanSatFlux project, Grant No. 4000125730/18/NL/FF/gp). This work further contributes to the NERC MOYA project (Grant No. NE/N015932/1).

Sediments cores collected aboard the RRS James Clark Ross (JR104) in the Bellingshausen Sea, 2004. This work was carried out as part of the first systematic investigation of the former ice drainage basin in the southern Bellingshausen Sea. Reconnaissance data collected on previous cruises JR04 (1993) and cruises of R/V Polarstern in 1994 and 1995 suggested that this area contained the outlet of a very large ice drainage basin during late Quaternary glacial periods. The data and samples collected allowed us to address questions about the timing and rate of grounding line retreat from the continental shelf, the dynamic character of the ice that covered the shelf, and its influence on glaciomarine processes on the adjacent continental slope.