During the ice stations, sea ice, brine/slush, snow and under-ice water sampling were collected for oxygen isotopic ratio. Ice cores were collected using a Kovacs 9 cm diameter ice corer. The ice core for oxygen isotopic ratio was cut directly after retrieval with a stainless steel folded saw. The core was cut generally into 10 cm sections (20 cm when ice cores were higher than 200 cm) and put into zip-lock polyethylene bags. Care was taken to use laboratory gloves when collecting the cores. For brine sampling, partial core holes were drilled into the ice (so called sackholes), usually to a depth of 25 cm and 50 cm. At site with flooding, brine collection was not possible, and samples of the surface slush were collected instead. Slush was collected by plastic shovel. Snow samples were also collected. Under-ice water was collected with a Teflon water sampler (GL Science Inc., Japan) 1, 3, 5 m below the bottom of the sea ice. In addition, CTD water sampling was examined at each station. The cores were taken back to the ship, and transferred to the gas tight bag (GL Science Inc., Japan), and then ice was melted at about +4 degrees C in a refrigerator. Melted samples were sub-sampled for each component. The snow samples were treated in the same manner as the sea ice samples for further analysis. Oxygen isotopic ratio was determined with a mass spectrometer (DELTA plus; Finnigan MAT, USA) in Hokkaido University. Oxygen isotopic ratio in per mil (parts per thousand) was defined as the deviation of H2 18O/H2 16O ratio of the measured sample to that of the standard mean ocean water (SMOW). The precision of oxygen isotopic ratio analysis from duplicate determinations is plus or minus 0.02 parts per thousand (Toyota et al., 2007). Data available: excel files containing sampling station name, dates, and oxygen isotopic ratio.

The Holocene sea-ice project brings together for the first time, records from the Antarctic continent and deep sea sediments that will allow us to calibrate three sea-ice extent surrogates, validate their use in contrast to satellite observations and explore climatic influence on the physio-ecological environment over the last 10,000 years. Spreadsheet 1 (appendix A): Complete list of Accelerator Mass Spectrometry (AMS) dating completed on E27-23 from various identified sources with original 14CAge and reported error. Three dates identified as Burckle pers comm. here were provided by Dr Lloyd Burckle (LDEO) to Dr L. Armand for this work. Outlier attributions are identified; the term Averaged identifies the two samples where final calibrated dates were averaged in this work. All remaining AMS dates were converted to calendar ages using the linear-based CALIB07 (Stuiver and Reimer, 1993) with calibration to the Marine13 dataset (Reimer et al., 2013) at 95% confidence (sigma 2) and included a correction for the surface water reservoir age of ~752 years at the site of core E27-23 resolved from the marine radiocarbon reservoir correction database and software available from http://radiocarbon.LDEO.columbia.edu/ (Butzin et al., 2005). The percent Marine Carbon relative attribution is provided. The Median age (Cal Yr BP) used as the final age at each respective (mid) depth is provided. In Appendix A the dates are all ages in years, however some are uncalibrated ages and others are Cal yr BP (= calendar years before present). So in terms of headings in Table A: Raw 14C age yr BP - is the raw age provided by radiocarbon dating without any corrections applied. It is in years before present. Corrected raw age (RA=752) - is the raw age with a local RA (Reservoir Age) correction applied and is still in years before present. The remaining ages are calendar years before present having been calibrated. All formats follow recommendations for reporting raw 14C dates and their calibration ages. Spreadsheet 2 (appendix B): Comparison of calibration output from the input of accepted 14C dates using OXCAL 4.2 (Bronk Ramsey 2009; Blaauw 2010), and CALIB07 (Stuiver and Reimer, 1993), both using the Marine13 calibration curve (Reimer et al., 2013) at 95.4% confidence (sigma 2) and including a correction for the surface water reservoir age of ~752 years at the site of core E27-23. The calibration output difference between the median Cal Yr BP, regardless of calibration method employed, was greater than or equal to 40 Cal Yr BP. Calibration data from the output of CALIB07 has been used in this paper to determine chronostratigraphy. Spreadsheet 3 (appendix C): The foraminiferal stable isotope data from E27-23. Ratios of oxygen (delta 18O) measured from the planktonic foraminifer Neogloboquadrina pachyderma sinistral (greater than 150 microns). Isotope values are reported as per mil (%) deviations relative to the Vienna Peedee Belemnite (VPDB). Spreadsheet 4 (appendix D): The paleo winter sea-ice concentration (wSIC) estimates for marine sediment core SO136-111. The calendar ages, in thousands of years before present (kyr BP), are provided for each sample from core SO136-111. For each of the samples in core SO136-111, we have provided the estimates winter sea-ice concentration (%), along with the associated lower and upper bounds for the 95% confidence interval around the estimated winter sea-ice concentration (%), for both GAM/WSI/13 and GAM/WSI/ETS. The final two columns provide the estimated average annual monthly sea-ice cover for each sample within core SO136-111, originally estimated using the Modern Analogue Technique, by Crosta et al. (2004). Finally, we provide the estimated summer sea surface temperature, again using the Modern Analogue Technique, from Crosta et al. 2004. Spreadsheet 5 (appendix E): The paleo wSIC estimates for marine sediment core E27-23. The calendar ages, in thousands of years before present are provided for each sample from core E27-23. For each of the samples in core E27-23, we have provided the estimated winter sea-ice concentration (%), along with the associated lower and upper bounds for the 95% confidence interval around the estimates for winter sea-ice concentration (%).

This dataset contains routine measurements of snow and ice thickness, and snow-ice interface temperature, at 1m intervals along standard transects; snow property characterisation in snow pits measured at 0m, 50m and 100m along the transects; and sea ice cores acquired at various locations both along the transects and elsewhere on ice station floes during the 2012 SIPEX 2 marine science voyage. Ice temperature information is acquired from the cores, which are taken on-board for further analysis. The latter includes thin-section analysis of sea-ice stratigraphy and crystallography at -20C within the freezer lab on-board the ship. The cores are then cut up into 5cm sections and melted for analysis of salinity and stable oxygen isotopes. Observation items: Snow: - Thickness - Temperature profile (every 3 cm) - Snow-ice interface temperature at 1m intervals along the 100m transects - Grain size - Grain shape - Density - Hardness - Salinity - Stable oxygen isotope Ice: - Thickness - Freeboard - Draft - Temperature - Salinity - Stable oxygen isotope - Crystallography and texture - Density Instruments: Snow: Folding scales, Spatula, Thermometer, Snow sampler, Magnifying glass, Salinometer, Temperature and thickness probes, scales Ice: Drills, corers, ice-thickness tape measures, thermometer, salinometer, band-saw, cross-polarising filter, scales The data are recorded in log books (scanned copies are included in this dataset) and have been transferred into the standard AAD sea-ice database templates (in excel format) for each station.