The Southern Ocean is one the most significant regions on earth for regulating the build up of anthropogenic CO2 in the atmosphere, and the capacity for carbon uptake in the region could be altered by climate change. The project aims to establish a time series of anthropogenic carbon accumulation. The work will be used to identify processes regulating the CO2 uptake and to test models that predict future uptake. These data were collected on the VMS voyage of the Aurora Australis in the 2010-2011 field season. Data include pH, carbon dioxide, alkalinity and spectrometer data.

Thermosalinograph data - one text file per day has been collected. Data include date, time, temperature, conductivity, salinity, location. Measurements were made on the CEAMARC voyage of the Aurora Australis - voyage 3 of the 2008-2008 summer season. See other CEAMARC metadata records for more information.

Total carbon dioxide and total alkalinity analysis of niskin bottle samples collected on CTD casts. All data have been stored in a single excel file. Measurements were made on the CEAMARC voyage of the Aurora Australis - voyage 3 of the 2008-2008 summer season. See other CEAMARC metadata records for more information.

The embryonic development of Antarctic krill (Euphausia superba) is sensitive to elevated seawater CO2 levels. This data set provides the experimental data and WinBUGS code used to estimate hatch rates under experimental CO2 manipulation, as described by Kawaguchi et al. (2013). Kawaguchi S, Ishida A, King R, Raymond B, Waller N, Constable A, Nicol S, Wakita M, Ishimatsu A (2013) Risk maps for Antarctic krill under projected Southern Ocean acidification. Nature Climate Change (in press) Circumpolar pCO2 projection. To estimate oceanic pCO2 under the future CO2 elevated condition, we computed oceanic pCO2 using a three-dimensional ocean carbon cycle model developed for the Ocean Carbon-Cycle Model Intercomparison Project (2,3) and the projected atmospheric CO2 concentrations. The model used, referred to as the Institute for Global Change Research model in the Ocean Carbon-Cycle Model Intercomparison Project, was developed on the basis of that used in ref. 4 for the study of vertical fluxes of particulate organic matter and calcite. It is an offline carbon cycle model using physical variables such as advection and diffusion that are given by the general circulation model. The model was forced by the following four atmospheric CO2 emission scenarios and their extensions to year 2300. RCP8.5: high emission without any specific climate mitigation target; RCP6.0: medium-high emission; RCP 4.5: medium-low emission; and RCP 3.0-PD: low emission (1). Simulated perturbations in dissolved inorganic carbon relative to 1994 (the Global Ocean Data Analysis Project (GLODAP) reference year) were added to the modern dissolved inorganic carbon data in the GLODAP dataset (5). To estimate oceanic pCO2, temperature and salinity from the World Ocean Atlas data set (6) and alkalinity from the GLODAP data set were assumed to be constant. Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators—whales, seals and penguins. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700–1,000m, where the carbon dioxide partial pressure (pCO2 ) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO2, and present a circumpolar risk map of krill hatching success under projected pCO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO2 emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem. The risk_maps folder contains the modelled risk maps for each of the climate change scenarios (i.e. Figure 4 in the main paper, and Figure S2 in the supplementary information). These are in ESRI gridded ASCII format, on a longitude-latitude grid with 1-degree resolution. Refs: 1. Meinshausen, M. et al. The RCP greenhouse gas concentrations and their extensions from 1765 to 2300. Climatic Change 109, 213-241 (2011). 2. Orr, J. C. et al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681-686 (2005). 3. Cao, L. et al. The role of ocean transport in the uptake of anthropogenic CO2. Biogeosciences 6, 375-390 (2009). 4. Yamanaka, Y. and Tajika, E. The role of the vertical fluxes of particulate organic matter and calcite in the oceanic carbon cycle: Studies using an ocean biogeochemical general circulation model. Glob. Biogeochem. Cycles 10, 361-382 (1996). 5. Key, R. M. et al. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP). Glob. Biogeochem. Cycles 18, GB4031 (2004). 6. Conkright, M. E. et al. World Ocean Atlas 2001: Objective Analyses, Data Statistics, and Figures CD-ROM Documentation (National Oceanographic Data Center, 2002).

Hydrochemistry of surface water. Parameters measured=salinity, oxygen, co2, oxygen isotope species, nutrients. All data have been stored in a single excel file. Measurements were made on the CEAMARC voyage of the Aurora Australis - voyage 3 of the 2008-2008 summer season. See other CEAMARC metadata records for more information.

Oceanographic measurements were collected aboard Aurora Australis cruise au1203, voyage 3 2011/2012, from 5th January to 12th February 2012. The cruise commenced with opportunistic CTD's in the region of the Adelie Depression and the former Mertz Glacier ice tongue, followed by a full south to north occupation of the CLIVAR/WOCE meridional section I9S. A total of 95 CTD vertical profile stations were taken on the cruise, most to within 15 metres of the bottom. Over 1500 Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients (phosphate, nitrate+nitrite and silicate), dissolved inorganic carbon (i.e. TCO2), alkalinity, pH, barium (dissolved), and biological parameters, using a 24 bottle rosette sampler. Full depth current profiles were collected by an LADCP attached to the CTD package, while upper water column current profile data were collected by a ship mounted ADCP. Meteorological and water property data were collected by the array of ship's underway sensors. An array of 5 current meter moorings was recovered from the Antarctic continental slope at the south end of the I9S transect.

Oceanographic measurements were collected aboard Aurora Australis cruise au1402, voyage 2 2014/2015, from 5th December 2014 to 25th January 2015. The cruise commenced with a Casey resupply, followed by work around the Dalton Polynya/Moscow University Iceshelf/Totten Glacier system, and then around the Mertz Glacier region. A total of 141 CTD vertical profile stations were taken on the cruise, most to within 11 metres of the bottom. Over 1000 Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients (phosphate, nitrate+nitrite and silicate), dissolved inorganic carbon (i.e. TCO2), alkalinity, helium, 18O, and biological parameters, using a 24 bottle rosette sampler. Full depth current profiles were collected by an LADCP attached to the CTD package, and bottom video footage was collected by a camera system (also mounted to the CTD package) for most casts. Upper water column current profile data were collected by a ship mounted ADCP. An underway CTD system (P.I. Alex Orsi, Texas A and M University) was used to collected measurements from the aft of the ship along several small transects around the Dalton Polynya. Meteorological and water property data were collected by the array of ship's underway sensors. 10 'Argo equivalent' floats were also deployed in both the Totten and Mertz regions, for an ice float pilot study. Six oceanographic moorings were recovered from around the Dalton Polynya, three Australian and three US (for the US moorings: P.I.'s Alex Orsi, Texas A and M University, Amy Leventer, Colgate University, and Eugene Domack, University of South Florida). Three temporary acoustic sound source moorings were also deployed then recovered in the same area, in support of an autonomous glider deployment (P.I. Craig Lee, University of Washington). Three oceanographic moorings were recovered from the Mertz region, two Australian and one French (P.I. Marie-Noelle Houssais, Universite Pierre et Marie Curie, for the French mooring). The data set here includes the CTD and Niskin bottle data, in both text and matlab format. The included README file gives full details on file formats.

Oceanographic measurements were collected aboard New Zealand’s National Institute for Water and Atmospheric Research (NIWA) research vessel RV Tangaroa, cruise ta1302 (i.e. NIWA cruise tan1302), from 3rd February to 13th March 2013, sailing from and returning to Wellington. The cruise commenced with a series of stations at the southern end of CLIVAR/WOCE meridional section SR3, followed by work around and offshore of the former Mertz Glacier ice tongue and the Mertz Depression. A series of stations were then taken along 150E and CLIVAR/WOCE zonal section S4, followed by a series of stations on the Campbell Plateau on the transit back to New Zealand. Details of all programs on the cruise, including lowered ADCP data, carbon sampling, geological coring and grabs, bottom camera footage, multibeam data, Argo float deployments and cruise participants, can be found in the voyage report (“RV Tangaroa Voyage Report, Tan1302 – Mertz Polynya Voyage”, unpublished NIWA report, authored by voyage participants). This report discusses the oceanographic data from CTD operations on the cruise. The original primary aim of the cruise was recovery and redeployment of an array of Australian (ACECRC) and French (LOCEAN) moorings in the Mertz region, along with CTD data collection on the shelf. Sea ice cover prevented access by Tangaroa (for the most part) to the shelf, and to any of the mooring sites, and so a secondary project was undertaken - collecting CTD’s on the slope and in canyons offshore of the sea ice. A total of 86 CTD vertical profile stations were taken on the cruise, most to within 12 metres of the bottom. Over 1400 Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients (silicate and nitrate+nitrite), dissolved inorganic carbon (i.e. TCO2), alkalinity, and isotopes (oxygen, hydrogen and carbon), using a 24 bottle rosette sampler. Full depth current profiles were collected by an LADCP attached to the CTD package. Meteorological and water property data were collected by the array of ship's underway sensors. The vessel mounted ADCP, rigged to a pole in the ship’s moonpool, was lost on the transit south. This report describes the processing/calibration of the CTD data, and details the data quality.

Oceanographic measurements were conducted along CLIVAR Southern Ocean meridional repeat transect SR3 between Tasmania and Antarctica from October to December 2001. A total of 135 CTD vertical profile stations were taken, more than half to within 20 m of the bottom. Over 2200 Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients, CFC's, CCl4, dissolved inorganic carbon, alkalinity, 13C, DMS/DMSP/DMSO, halocarbons, barium, barite, ammonia, del30Si, dissolved and particulate organic carbon, particulate silica, 15N-nitrate, 18O, 234Th, 230Th, 231Pa, primary productivity and biological parameters, using a 24 bottle rosette sampler. Near surface current data were collected using a ship mounted ADCP. Two sediment trap moorings were serviced, and a third mooring was deployed at a new location. A summary of all CTD data and data quality is presented in the data report. This work was completed as part of ASAC project 1335.

Oceanographic measurements were conducted in the Southern Ocean around Heard and McDonald Islands, and in the Prydz Bay region, from January 1992 to March 1992. A total of 168 CTD (conductivity, temperature and depth) vertical profile stations were taken, most to near bottom. Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients (phosphate, nitrate+nitrite, silicate), chlorofluorocarbons, helium, tritium, dissolved inorganic carbon, alkalinity, carbon isotopes, dissolved organic carbon, dimethyl sulphide/dimethyl sulphoniopropionate, iodate/iodide, oxygen 18, primary productivity, and biological parameters, using a 24 bottle rosette sampler. CTD salinity data have been calibrated against bottle samples, although the calibration quality varies over the cruise. CTD salinity accuracies can be summarised as follows: Stations 1-26: no bottle samples; conductivity calibration from later stations applied; accuracy therefore unknown. Stations 27-102: accuracy approximately 0.005 (PSS78). Stations 83-93: residuals a bit lower than surrounding stations: data uncertainty may be slightly increased. Stations 103-111: no bottle samples; conductivity calibration from surrounding stations applied; accuracy therefore unknown. Stations 112-168: significant increase in data scatter; accuracy approximately 0.010 (PSS78). The bottle data file contains salinities and nutrients. Dissolved oxygen data exist only as titration values recorded on the laboratory analysis sheets. The nutrient data show a fair amount of scatter, particularly when looking at the nitrate vs phosphate ratios. These data should be used with caution. Measurement and data processing techniques are described, and a summary of the data are presented in graphical and tabular form. The fields in this dataset are: oceanography ship station number date start time bottom time finish time cruise start position bottom position finish position maximum position bottom depth pressure temperature (T-90) salinity sigma-T specific volume anomaly geopotential anomaly dissolved oxygen fluorescence photosynthetically active radiation niskin bottle number