Data measured during the Tara Oceans Pacific Expedition, 2016-2018

This data describe a set of sea-ice and seawater physical and biochemical parameters obtained from seawater samples and ice cores drilled from land fast sea ice in the vicinity of Davis Station, East Antarctica at six different dates (stations 1-6) during late Spring 2016. Stations 1: 16 Nov. 2016 Stations 2: 21 Nov. 2016 Stations 3: 23 Nov. 2016 Stations 4: 26 Nov. 2016 Stations 5: 29 Nov. 2016 Stations 6: 02 Dec. 2016 Parameters measured: - Temperature, salinity; - Iron: Dissolved (less than 0.2um), soluble (less than 0.02um) colloidal (between 0.02 and 0.2um) and Particulate fractions (greater than 0.2um); - Macronutrients: Nitrate (NO3), nitrite (NO2), silicate (Si), phosfate (PO4) and ammonium (NH4); - Chlorophyll-a (Chla); - Particulate Organic Matter: Particulate Organic Carbon (POC) and Particulate Organic Nitrogen (PON) SW0: seawater collected at the surface SW3: seawater collected at 3m depth SW10: seawater collected at 10m depth

Oceanographic measurements were collected aboard Aurora Australis cruise au1602, voyage 2 2016/2017, from 8th December 2016 to 21st January 2017. The cruise commenced with a Casey resupply, followed by work around the Dalton Polynya/Moscow University Iceshelf, then the Mertz Glacier region, and then around the Ninnis Polynya. 14 stations at the southern end of the SR3 transect were also completed. Ice conditions prevented access to the front of the Totten Glacier. A total of 73 CTD vertical profile stations were taken on the cruise, most to within 12 metres of the bottom (Table 1). Over 800 Niskin bottle water samples were collected for the measurement of salinity, dissolved oxygen, nutrients (phosphate, nitrate+nitrite, silicate, ammonia and nitrite), dissolved inorganic carbon (i.e. TCO2), alkalinity, Th-234, POC, Chla, PAM, HPLC, Nd, Po-210/Pb-210, bacteria, O-18, caesium, and Teflon pollutants, using a 24 bottle rosette sampler. Full depth current profiles were collected by an LADCP attached to the CTD package. 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. 8 Argo floats were also deployed (Table 13) on the transit from Hobart to Casey. The data set contains CTD dbar data and Niskin bottle data (i.e. core hydrochemistry only - salinity, dissolved oxygen and nutrients). A detailed data report is included, with a description of the data and important data quality information.

The circumpolar Subantarctic Zone (SAZ) is a globally significant region of water mass formation and carbon dioxide uptake from the atmosphere. Here we synthesise the results of nine voyages over 8 years to describe the seasonal variation in mixed layer properties in the SAZ south of Australia for comparison with biogeochemical process studies carried out in late summer (March 1998) as part of the SAZ Project. Winter mixing extends to depths greater than 400 m, resulting in the formation of Subantarctic Mode Water. In summer the mixed layer shoals to 75-100 m, depths which are still sufficiently deep that phytoplankton growth may be light limited. Nitrate and phosphate concentrations are reduced in summer( e.g., nitrate decreases from greater than 15 to less than 5/ micro mol kg- 1) but remain well above limiting levels. Silicate in contrast, is low throughout the year (4/micro mol kg- 1 in winter and less than 2 / micro mol kg- 1 in summer). Water mass properties along a north-south hydrographic section in March 1998 suggest that near-surface waters spread from south to north across the Subantarctic Front (SAF), supplying cool, fresh, nutrient-rich water to the SAZ. As a consequence, the properties of the southern SAZ differ from those farther north: the mixed layer in the south is cooler, fresher, deeper, higher in nutrients, and bounded below by a halocline (rather than by a seasonal thermocline, as in the northern SAZ). The contrast between the northern and southern SAZ persists throughout the year, suggesting the cross-front exchange occurs year-round and likely contributes to the differences in seasonal thermal amplitude and algal biomass accumulation seen in satellite images. Density-compensated horizontal gradients of temperature and salinity are common in the mixed layer of the SAZ and the northern SAF, consistent with the hypothesis that the vigour of lateral mixing in the mixed layer is a strong function of the magnitude of the lateral density gradient. CTD Data are available for access via the provided URL. Data from the following voyages of the Aurora Australis were used: 1991-1992 Voyage 1 1992-1993 Voyage 9 1994-1995 Voyage 4 1994-1995 Voyage 7 1995-1996 Voyage 1 1996-1997 Voyage 1 1997-1998 Voyage 6

Data were collected during the 1997-1998 austral summer on voyages by the Aurora Australis and Southern Surveyor. Oceanographic processes in the subantarctic region contribute crucially to the physical and biogeochemical aspects of the global climate system. To explore and quantify these contributions, the Antarctic Cooperative Research Centre (CRC) organised the SAZ Project, a multidisciplinary, multiship investigation carried out south of Australia in the austral summer of 1997-1998. Ammonia data were collected by Ros Watson (and provided by Tom Trull), and as of 2012, are unpublished.

Oceanographic measurements were collected aboard Aurora Australis cruise au1603, voyage 3 2015/2016, from 11th January to ~24th February 2016. The cruise commenced with the K-AXIS project, the major marine science component of the cruise. This was the Australian component (P.I.’s Andrew Constable, Steve Rintoul and others) of a combined biological and oceanographic study in the vicinity of the Kerguelen Axis. After conclusion of marine science work the ship went to Mawson for a resupply. During a storm on 24th February the ship broke free of its mooring lines and ran aground on the rocks at West Arm in Horseshoe Harbour, thus ending the cruise. Expeditioners were eventually taken to Casey on the Shirase, then flown home. Meanwhile the Aurora Australis was refloated and sailed to Fremantle, then on to Singapore for repairs. This report discusses the oceanographic data from CTD operations on the cruise. A total of 47 CTD vertical profile stations were taken on the cruise (Table 1). Over 850 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, POC and PN, and biological parameters, using a 24 bottle rosette sampler. A UVP particle counter/camera system was attached to the CTD package (P.I. Emmanuel Laurenceau). A separate trace metal rosette system was deployed from the trawl deck (P.I. Andrew Bowie). Upper water column current profile data were collected by a ship mounted ADCP, and meteorological and water property data were collected by the array of ship's underway sensors. Eight drifting floats were deployed over the course of the cruise. Processing/calibration and data quality for the main CTD data are described in this report. Underway sea surface temperature and salinity data are compared to near surface CTD data. CTD station positions are shown in Figure 1, while CTD station information is summarised in Table 1. Float deployments (5 x Argo/Apex, 2 x SOCCOM and 1 x Provor) are summarised in Table 10. Further cruise itinerary/summary details can be found in the voyage leader report (Australian Antarctic Division unpublished report: Voyage 3 2015-2016, RSV Aurora Australis, Voyage Leader’s report - see the metadata record "Aurora Australis Voyage 3 2015/16 Track and Underway Data" for access to the Voyage Report).

We report on the late winter oceanography observed beneath Antarctic sea ice offshore from the Sabrina and BANZARE coast of Wilkes Land, East Antarctica (115- 125 E) in September-October 2007 during the Sea Ice Physics and Ecosystem eXperiment (SIPEX) research voyage. A pilot program using specifically designed 'through-ice' Conductivity-Temperature-Depth (CTD) and acoustic Doppler current profiling (ADCP) systems was conducted to opportunistically measure water mass properties and ocean currents during major ice stations. This project involved two independent sub-ice observation platforms: A winch-driven Conductivity-Temperature-Depth system for measuring basic water mass properties and an acoustic Doppler current profiling (ADCP)/GPS system for measuring ocean currents and ice drift. Hereafter these are referred to as the CTD and ADCP systems respectively. The CTD system comprised of an Falmouth Scientific Institute (FSI) CTD instrument, a tripod and over 1000m of polyethylene rope on a winch/drum attached to a metal sled.

3 CTD casts were conducted during a limited marine science voyage by the Nella Dan to Prydz Bay during the 1985-1986 summer Antarctic season. The voyage leaser was Tom Maggs, and the deputy leader was Peter Heyward. The ship followed the schedule listed out below: Hobart 29-Dec-1985 04-Jan-1986 Edgeworth David 13-Jan-1986 17-Jan-1986 Shackleton Ice Shelf Davis 21-Jan-1986 21-Jan-1986 Marine Science 22-Jan-1986 23-Jan-1986 Marine Science Prydz Bay Davis 24-Jan-1986 26-Jan-1986 Marine Science 27-Jan-1986 27-Jan-1986 Marine Science Prydz Bay Mawson 29-Jan-1986 01-Feb-1986 Davis 03-Feb-1986 04-Feb-1986 Mawson 06-Feb-1986 06-Feb-1986 Davis 09-Feb-1986 09-Feb-1986 Edgeworth David 13-Feb-1986 13-Feb-1986 Shackleton Ice Shelf Casey 14-Feb-1986 14-Feb-1986 Hobart 22-Feb-1986 24-Feb-1986

Oceanographic measurements conducted on voyage 6 of the Aurora Australis of the 2000-2001 season. These data comprise CTD (Conductivity, Temperature and Depth) and ADCP (Acoustic Doppler Current Profiler) data. These data were collected by Mark Rosenberg. This metadata record was completed by AADC staff when the data were discovered bundled with acoustics data during a data cleaning exercise. Basic information about voyage 6: The voyage will complete a range of Marine Science activities off the Mawson Coast, and off the Amery Ice Shelf before calling at Davis to retrieve summer personnel and helicopters prior to returning to Hobart. Science equipment calibration will be undertaken at Mawson. (Marine Science activities were interrupted when the Aurora Australis was required to provide assistance in the Polar Bird's attempt to reach Casey, complete the station resupply and return to open water.) Leader: Dr Graham Hosie Deputy Leader: Mr Andrew McEldowney See the readme files in the downloads for more information.