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.

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.

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.

Radiolarian data from IN2017_V01 These data were generated by Kelly-Anne Lawler (corresponding author, kelly-anne.lawler@anu.edu.au) with taxonomic assistance from Dr Giuseppe Cortese. These data are based on samples collected during voyage IN2017_V01 of the RV Investigator, co-chief scientists, Leanne Armand and Phil O’Brien. The IN2017-V01 post-cruise report is available through open access via the e-document portal through the ANU library. https://openresearch-repository.anu.edu.au/handle/1885/142525 The preferred citation is: L.K. Armand, P.E. O’Brien and On-board Scientific Party. 2018. Interactions of the Totten Glacier with the Southern Ocean through multiple glacial cycles (IN2017-V01): Post-survey report, Research School of Earth Sciences, Australian National University: Canberra, http://dx.doi.org/10.4225/13/5acea64c48693 Samples for radiolarian analysis were collected on board immediately after core recovery. Samples were air dried at ambient temperature (~21 degrees C), and their processing in preparation for microscopy was based on the method of Cortese and Prebble (2015). Cover slips were adhered to the slides using Canada Balsam and slides were observed using Olympus BH-2 inverted light microscope at up to 400x magnification. Slides were first counted to determine absolute radiolarian abundance (ARA) and, for samples where ARA was high enough, more than 400 individuals were identified per sample to species/subspecies or genus level. Taxonomic nomenclature used while preparing the dataset was per Lazarus et al. (2015) with additional clarification sought from the World Register of Marine Species (WoRMS Editorial Board, 2018) and radiolaria.org (radiolaria.org, 2018). Station_core Longitude Latitude C013_KC05 119.0183 -64.6538 C022_KC11 120.049 -65.1313 These data were collected to provide palaeoceanographic information. Cortese, G., and Prebble, J. (2015). A radiolarian-based modern analogue dataset for palaeoenvironmental reconstructions in the southwest Pacific. Marine Micropaleontology, 118, 34-49. WoRMS Editorial Board, (2018). World Register of Marine Species. Available from http://www.marinespecies.org at VLIZ. Lazarus, D. B., Suzuki, N., Caulet, J.-P., Nigrini, C., Goll, I., Goll, R., Dolven, J.K. Diver, P. and Sanfilippo, A., (2015). An evaluated list of Cenozic-Recent radiolarian species names (Polycystinea), based on those used in the DSDP, ODP and IODP deep-sea drilling programs. Zootaxa, 3999(3), 310-333. radiolaria.org, 2018. radiolaria.org, (http://www.radiolaria.org/) Kelly-Anne Lawler and Giuseppe Cortese unpublished data

Diatom data from IN2017_V01: These data were generated by Amy Leventer (aleventer@colgate.edu) and undergraduate students at Colgate University, including Isabel Dove, Meghan Duffy, and Meaghan Kendall. All questions regarding the specifics of these data should be directed to Amy Leventer. These data are based on samples collected during research cruise IN2017_V01 of the RV Investigator, co-chief scientists, Leanne Armand and Phil O’Brien. The IN2017-V01post-cruise report is available through open access via the e-document portal through the ANU library. https://openresearch-repository.anu.edu.au/handle/1885/142525 The document DOI: 10.4225/13/5acea64c48693 The preferred citation is: L.K. Armand, P.E. O’Brien and On-board Scientific Party. 2018. Interactions of the Totten Glacier with the Southern Ocean through multiple glacial cycles (IN2017-V01): Post-survey report, Research School of Earth Sciences, Australian National University: Canberra, http://dx.doi.org/10.4225/13/5acea64c48693 Samples for diatom analysis were collected on board ship immediately after core recovery. Samples were dried in an oven at 50 degrees C prior to analytical work. Quantitative diatom slides were prepared according to the settling technique of Warnock and Scherer (2014). Cover slips were adhered to the slides using Norland Optical Adhesive #61. Slides were observed under Olympus CX31, BX50 and BX60, and Zeiss Primo Star light microscopes, using a 100X oil immersion objective for a total magnification of 1000X. A minimum of 400 valves or 10 transects was counted for each slide, depending on the absolute diatom abundance. Interglacial samples were relatively diatom-rich, consequently counts of 400 specimens were possible. However, most glacial samples were diatom-poor, making it very difficult and time-consuming to count 400 specimens. Under these conditions, 10 transects were counted, as has been done in previous studies of sediments with very low diatom concentrations (Rebesco et al., 2014). Valves were only counted if greaster than 50% complete. Diatoms were identified to species level when possible (Crosta et al., 2005; Armand et al., 2005; Cefarelli et al., 2010). Occurrences of biostratigraphic markers were noted and tallied concurrently. Species were considered extinct when observed stratigraphically higher than extinction boundaries as identified by Cody et al. (2008). Station_core Longitude Latitude A005_KC02_PC01 115.623 -64.471 A006_KC03 115.043 -64.463 A042_KC14 116.6403 -64.5387 C012_KC04_PC05 119.3012 -64.675 C013_KC05 119.0183 -64.6538 C015_KC06 118.696 -64.729 C018_KC07 118.498 -64.401 C020_KC08 119.739 -64.794 C022_KC11 120.049 -65.1313 C025_KC12_PC08 120.8635 -64.9538 C038_KC13 119.1035 -64.4828 Armand, L.K., X. Crosta, O. Romero, J. J. Pichon (2005), The biogeography of major diatom taxa in Southern Ocean sediments: 1. Sea ice related species, Paleogeography, Paleoclimatology, Paleoecology, 223, 93-126. Cefarelli, A.O., M. E. Ferrario, G. O. Almandoz, A. G. Atencio, R. Akselman, M. Vernet (2010), Diversity of the diatom genus Fragilariopsis in the Argentine Sea and Antarctic waters: morphology, distribution and abundance, Polar Biology, 33(2), 1463-1484. Cody, R., R. H. Levy, D. M. Harwood, P. M. Sadler (2008), Thinking outside the zone: High-resolution quantitative diatom biochronology for the Antarctic Neogene, Palaeogeography, Palaeoclimatology, Palaeoecology, 260, 92-121, doi:10.1016/j.palaeo.2007.08.020 Crosta, X., O. Romero, L. K. Armand, J. Pichon (2005), The biogeography of major diatom taxa in Southern Ocean sediments: 2. Open ocean related species, Palaeogeography, Palaeoclimatology, Palaeoecology, 223, 66-92. Rebesco, M., E. Domack, F. Zgur, C. Lavoie, A. Leventer, S. Brachfeld, V. Willmott, G. Halverson, M. Truffer, T. Scambos, J. Smith, E. Pettit (2014), Boundary condition of grounding lines prior to collapse, Larson-B Ice Shelf, Antarctica, Science, 345, 1354-1358. Warnock, J. P., R. P. Scherer (2014), A revised method for determining the absolute abundance of diatoms, J. Paleolimnol., doi:10.1007/s10933-014-9808-0 These data were collected to provide paleoceanographic and biostratigraphic information. Amy Leventer, Isabel Dove, Meghan Duffy, and Meaghan Kendall unpublished data

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.

During voyage 1 of 1985, sixteen ice cores were drilled from sea ice. Details from those cores include the position they were drilled, length of the core, percentage of the core that was frazil ice, and comments on the state of the core, or observations of the ice make-up. Physical records are archived at the Australian Antarctic Division.

Metadata record for data from ASAC Project 2534 See the link below for public details on this project. 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. Taken from the 2004-2005 Progress Report: Progress Objectives: Our objective is to instigate synthesis between deep sea and continental ice core records of Antarctic sea ice variability over the Holocene (last 10,000 yrs BP). The relevance of this novel evaluation is three-fold: - To appraise for the first time the relationships between proxy sea ice predictions beyond the instrumental record from the land and sea. - To assess variability differences and similarities from the various records that can then be used to probe the dynamics of the climate/environmental system in the East Antarctic sector. - To provide insights on the ecological response sea ice plays through the Holocene. Public summary of the season progress: Basic analysis of samples from Core E27-23 have been complete except for seven new samples from near the top of the core. This includes counts of diatoms, foraminifera, ice-rafted debris, volcanic glass. A greater variety of parameters is available than expected. Dramatic downhole changes represent oceanographic changes over last 25 000 years at the site including in evidence for carbonate dissolution and water temperature. Now needs statistical analysis of diatom data, extra radiocarbon dates and integration with data from Law Dome ice-core.