Depth to sea floor and sea ice thickness data measured at various locations around the Vestfold Hills, Davis station, East Antarctica, during the 2018-19 austral summer. Depth to sea floor and sea ice thickness measures in meters obtained using a weighted tape measure deployed through a hole (5 cm) drilled in the sea ice. Sea ice thickness was determined by snagging the weight on the underside edge of the ice hole as the tape measure was retreived.

This file comprises five high-resolution records of 10Be concentration in snow from Law Dome, East Antarctica: DSS0102-pit, DSS0506-pit, DSS0506-core, DSS0809-core and DSS0910-core. A single composite series is constructed from three of these records (DSS0506-core, DSS0809-core and DSS0102-pit), providing a monthly-resolved time-series of 10Be concentrations at DSS over the decade spanning 1999 to 2009. This work was done as part of AAS 2384, AAS 3064 and AAS 1172. A data update was provided by Jason Anderson on 2012-12-17.

Overview of the project and objectives: Assessing the contribution of the different N substrates to the primary production process, such as the biogenic silica production and dissolution in the Antarctic sea-ice provides a means to understand the biogeochemical system functioning. In such a semi closed-type system, assess incorporation rates of HCO3-, NO3-, NH4+, SiOH4, BSi dissolution, nitrification, C-release in close-by ice-cores (3 ice-cores dedicated to (i) 13C-assimilation + 15NH4+ uptake rate, (ii) 13C-assimilation + 15NO3- uptake rate and nitrification, (iii) Biogenic silica production and dissolution via 30Si isotope tool) will allow improving the knowledge of system functioning. This is also closely linked to the thematic of iron availability since these experiments are done close to / on the Trace Metal site allowing us to hopefully propose a relatively complete image of biogeochemical activity and relationship with trace metals on this site. Methodology and sampling strategy: Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). 14C and 13C-incubation experiment intercalibration work were conducted on the Biosite (different place than TM site except for station 7) Incubation experiment samples are analyzed via (1) Elemental Analyzer - Isotope Ratio Mass Spectrometer (EA-IRMS) for carbon and nitrogen (VUB, Brussels, Belgium); (2) High Resolution Inductively Coupled Mass Spectrometer (HR-ICPMS) for silicon (RMCA, Brussels, Belgium).

Overview of the project and objectives: To investigate whether nitrate uptake and processes other than nitrate uptake by phytoplankton are significant and show spatial variability possibly induced by varying availability of Fe and other parameters in the region, seawater was collected from CTD (Conductivity, Temperature and Depth) and TMR (Trace Metals Rosette) casts jointly with the nutrient sampling, as well as well as sea-ice collected from Bio ice-core types on Ice Station, for analysis of nitrate d15N, d18O isotopic composition. Results have been interpreted in the light of prevailing nitrate-nutrient concentrations (Belgian team) and N-uptake regimes for the Ice Stations (new vs. regenerated production and nitrification; see Silicon, Carbon and Nitrogen in-situ incubation Metadata file). Methodology and sampling strategy: Samples for isotopic composition of nitrate were collected from the CTD rosette, TMR and Bio ice-core jointly with the nutrient sampling. Sea-ice sampling: sampling strategy follows ice stations deployment via Bio ice-core type. Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). All samples were filtered on 0.2 microns acrodiscs and kept at -20 degrees C till analysis in the home-based laboratory. We applied the denitrifier method elaborated by Sigman et al. (2001) and Casciotti et al. (2002). This method is based on the isotopic analysis of delta 15N and delta 18O of nitrous oxide (N2O) generated from nitrate by denitrifying bacteria lacking N2O-reductase activity. As a prerequisite the nitrate concentrations need to be known (nutrients analysis in the home lab.) as this sets sample amount provided to the denitrifier community. Briefly, sample nitrate is reduced by a strain of denitrifying bacteria (Pseudomonas aureofaciens) which transform nitrate into N2O, but lack the enzyme to produce N2. N2O is then analysed for N, O isotopic composition by IRMS (Delta V, Thermo) after elimination of CO2, volatile organic carbon and further cryogenic focusing of N2O (Mangion, 2011). Casciotti K.L., D.M.Sigman, M.G. Hastings, J.K. Bohlke and A. Hilkert, 2002. Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method, Analytical Chemistry, 74 (19): 4905-4912. Mangion P., 2011. Biogeochemical consequences of sewage discharge on mangrove environments in East Africa, PhD Thesis, Vrije Universiteit Brussel, 208 pp. Sigman D.M., Casciotti K.L., Andreani M., Barford C., Galanter M. and J.K. Bohlke, 2001. A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater, Analytical Chemistry, 73: 4145-4153.

This dataset is an annual reconstruction of the Interdecadal Pacific Oscillation (IPO), a decadal-scale mode of variability in the Pacific Ocean which has climate impacts across the Pacific Basin. This data is a time series spanning CE 1-2011 inclusive (ie, the Common Era). The time series is reconstructed from three primary annually-resolved proxy series from the Law Dome ice core. These three series are the log-transformed seasonal sea salt concentration for the cool season (June to November), the log-transformed seasonal sea salt concentration for the warm season (December to May) and the annual snowfall accumulation rate. The reconstruction uses a Gaussian kernel correlation reconstruction method (Roberts et al., 2019) with 2000 ensemble members, which provides a mean IPO index value for each year, as well as upper and lower quartiles. The reconstruction target time series was the observed Interdecadal Pacific Oscillation spanning 1870-2020, which had been smoothed using a Gaussian window of 13 years. This Gaussian kernel correlation reconstruction is an evolution/replacement of the method and reconstruction presented in Vance et al., (2015) to reconstruct the IPO. This is now our preferred dataset for the Law Dome IPO reconstruction, and supersedes that published by Vance et al., (2015). The time series (dataset) consists of three columns with column headings as follows: Year – where year is the year from the beginning of the Common Era, ie, ‘436.0’ means the year CE 436, and ‘2009.0’ means the year 2009. IPO (mean) – the mean of the IPO reconstruction index value Std Dev) – the standard deviation of the index value for each year.

Zooplankton were collected during the winter-spring transition during two cruises of the Aurora Australis: SIPEX in 2007 and SIPEX II in 2012. As part of the collections sea ice cores were collected to describe the ice habitat during the period of zooplankton collections. Ice cores were taken with a 20 cm diameter SIPRE corer and sectioned in the field with an ice core. Temperature was measured in the section using a spike thermometer and slivers of each section were melted without filtered water to record salinity. The remainders of each section were melted at 4oC in filtered seawater and the melted water was used to measure chlorophyll a concentration, and meiofauna species and abundance. Meiofauna were counted and identified using a Leica M12 microscope: to species in most cases and down to stage during 2012.

Twenty-six marine and lacustrine sediment cores were taken from Windmill Islands during the 1998/99 season. They have been analysed for physical, chemical and biological parameters by a multidisciplinary team under ASAC project 1071. The download file contains 12 Excel spreadsheets of data.

AM02 borehole drilled December 2000. Several caliper profiles obtained as a 'first look' at borehole closure rates. Consult Readme file for detail of data files and formats.

Note - these data should be used with caution. The chief investigator for the dataset has indicated that a better quality dataset exists, but the AADC have been unable to attain it for archive. In addition to snow pits dug by other groups, several snow pits were dug at IMB/AWS deployment sites and at snow mast sites. Dates, locations, personnel, and purpose are listed in Table 1. Many of the data files include the raw weight measurements including the mass of the snow density shovel along with the snow. This needs to be corrected using the snow density shovel weight appropriate to each pit. Table 1 Snow Pits (comma separated) Date,Location,Personnel,Comments 2012-10-04,Floe 3 radiometer site,Katie,Full-depth snow density profile for evaluation of SMP data 2012-10-08,Floe 4 drift mast,Katie,Full-depth snow density profile for evaluation of SMP data 2012-10-14,Floe 6 buoy 1,Katie,Full-depth snow density profile for evaluation of SAMS WHOI-3 data 2012-10-14,Floe 6 buoy 2,Katie,Full-depth snow density profile for evaluation of SAMS WHOI-5 data 2012-10-20,Floe 7 drift mast,Ted,Snow pit to characterise snow at ice station 7 drift mast site 2012-10-23,Floe 7 drift mast,Katie,Full-depth snow density profile for evaluation of SMP data 2012-10-28,Helicopter buoy install,Petra,Snow pit for evaluation of SAMS- WHOI-4 buoy data 2012-10-29,Helicopter buoy install,Petra,Snow pit for evaluation of SAMS- TASI2-1 buoy data 2012-11-01,Floe 8,Ted,Snow pit for evaluation of WHOI-2 buoy data 2012-11-04,Floe 6 buoy re-install,Ted,Snow pit for evaluation of WHOI-6 buoy data

AM01 borehole drilled January 2002. Data collected in series of files over a period of 2 days during production of borehole. Consult Readme file for detail of data files and formats.