Field-based sampling: As part of Australian Antarctic Science project # 4298, a total number of 44 sea ice sites were sampled for bio-optical measurements along 4 transects on land-fast sea ice off Davis Station (Antarctica) during November – December 2015. Measurements included simultaneous hyperspectral down-welling (ice surface) irradiance (triplicate) and under-ice radiance (triplicate) measurements (320 – 900 nm, 3.3 nm resolution) with a TriOS ACC and Trios ARC radiometer, respectively. The radiance measurements were conducted with the TriOS ARC radiometer mounted onto an L-shaped arm (for deployment details see Melbourne-Thomas et al. 2015). Subsequently, snow thickness was measured with a ruler and an ice core was collected directly above the radiometer location. Sea-ice freeboard (tape measure) and ice thickness (ice core length) were also recorded. Ice cores (9 cm internal diameter) were cut into sections, and these were melted in the dark at +4 degrees C, filtered onto GFF filters and then used to measure ice algal pigment content (using High Performance Liquid Chromatography (HPLC) and spectral ice algal absorption coefficients (ap, ad, aph) for entire vertical profiles or for the lower-most 0.1 m of ice cores. The location of the sampling grid had its origin (x=0, y=0) at GPS position: -68.568904, 77.945439. Transects (128m – 512 m in length) started at x=60, x=70, x=80 and x=90 m and were sampled at y-positions of 0m, 0.5m, 1m, 2m, 4m, 8m, 16m, 32m, 64m, 128m, (256m, and 512m) on 19/11/2015, 23/11/2015, 29/11/2015 and 02/12/2015, respectively. Analysis of ice algal chlorophyll a concentration: For pigment analysis, 0.25 to 1.0 litres of melted ice core subsamples were passed through 25 mm diameter glass-fiber (Whatman GF/F) filters. The filters were then frozen and stored below −80 degrees C prior to analysis using HPLC. Samples were extracted over 15 to 18 hours in acetone before analysis by HPLC using a modified C8 column and binary gradient system with an elevated column temperature [Van Heukelem and Thomas, 2001]. Pigments were identified by retention time and absorption spectra from a photo-diode array (PDA) detector, and concentrations were determined from commercial and international standards (Sigma; DHI, Denmark). Analysis of particulate (algal and non-algal) absorption: The optical density (OD) spectra of the particulate material on these filters (see section above) were measured over the 350 to 750 nm spectral range in 0.9 nm increments, using a Cintra 404 UV/VIS dual-beam spectrophotometer equipped with an integrating sphere. The pigments on the sample filter were then extracted using the method of Kishino et al. [1985]'s method to determine the OD of the non-algal particles in a second scan. The OD due to ice algae was then obtained by calculating the difference between the optical density of the total particulate and non-algal fractions. The OD measurements were converted to absorption spectra using blank filter measurements, and by first normalizing the scans to zero at 750 nm and then correcting for the path length amplification using the coefficients of Mitchell [1990]. A detailed description of the method is given in Clementson et al. [2001], and followed SeaWiFS protocols [Muller et al., 2003]. An exponential function was fitted to all spectra of non-algal particulate material: ad(λ) = ad(350 nm) exp[−S(λ − 350 nm)] + b, (1) where ad(λ) is the residual absorption coefficient over the wavelength (λ) range 350 to 750 nm of the particles after methanol extraction, also referred to as absorption of detritus [m−1] although this may include absorption of non-extractable pigments and heterotrophic protists. A non-linear least-squares technique was used to fit Equation 1 to the untransformed data, where S and b are empirically-determined constants. The inclusion of an offset b allows for any baseline correction. In some samples, pigment extraction was incomplete, leaving small residual peaks in detritus spectra at the principal chlorophyll absorption bands. To avoid distorting the fitted detritus spectra, data at these wavelengths were omitted when all spectra were fitted. Total particulate spectra were smoothed using a running box-car filter with 10 nm width, and the fitted detritus spectra were subtracted to yield the ice algae spectra. Subtracting fitted detritus spectra minimized any artifacts due to incomplete extraction of pigments. The resulting ice algae spectra were base-corrected by subtracting absorption at 750 nm to obtain aph(λ). The following parameters were then determined: ap(λ) = absorption coefficient of particles [m−1]; aph(λ) = absorption coefficient of ice algae [m−1] calculated as the difference between ap(λ) and ad(λ). Literature cited: Clementson, L. A., J. S. Parslow, A. R. Turnbull, D. C. McKenzie, and C. E. Rathbone (2001), Optical properties of waters in the Australasian sector of the Southern Ocean, Journal of Geophysical Research: Oceans, 106(C12), 31,611–31,625, doi:10.1029/2000jc000359. Kishino, M., M. Takahashi, N. Okami, and S. Ichimura (1985), Estimation of the spectral absorption-coefficients of phytoplankton in the sea, Bulletin of Marine Science, 37(2), 634–642.Melbourne-Thomas, J., K. Meiners, C. Mundy, C. Schallenberg, K. Tattersall, and
G. Dieckmann (2015), Algorithms to estimate Antarctic sea ice algal biomass from under-ice irradiance spectra at regional scales, Marine Ecology Progress Series, 536, 107–121, doi:10.3354/meps11396. Mitchell, B. G. (1990), Algorithms for determining the absorption coefficient for aquatic particulates using the quantitative filter technique, Orlando’90, 1302, 137–148, doi:10.1117/12.21440. Müller, J. L., R. R. Bidigare, C. Trees, W. M. Balch, and J. Dore (2003), Ocean Optics Protocols for Satellite Ocean Colour Sensor Validation, Revision 5, Volume V: Biogeochemical and Bio-Optical Measurements and Data, NASA Tech. Memo. Van Heukelem, L., and C. S. Thomas (2001), Computer-assisted high-performance liquid chromatography method development with applications to the isolation and analysis of phytoplankton pigments, Journal of Chromatography A, 910(1), 31–49, doi:10.1016/s0378-4347(00)00603-4.

AM01b borehole site Samples collected during drilling and scientific sampling phases of work. AWS continuing to operate (not a new station, but ongoing AM01 station).

AM01 borehole drilled January 2002. Samples collected during drilling and scientific sampling phases of work. AWS continuing to operate.

AM01 borehole drilled mid-January 2002. Profiling measurements conducted over a period of one week. Long term monitoring instruments installed 2002-01-16. AM01b borehole drilled mid-December 2003. Video recording of borehole walls and sea floor benthos. Sediment sample collected from sea floor.

AM01b borehole drilled mid-December 2003. Profiling measurements conducted over a period of a few days. Video recording of borehole walls and sea floor benthos. Sediment sample collected from sea floor. No long term monitoring instruments installed. AM01b borehole was drilled within a few hundred metres of where the ice shelf had carried the original AM01 borehole to, in the intervening 2 years. As the AM01 borehole had a mooring suite of instruments, none were emplaced in the AM01b borehole.

AM02 borehole drilled December 2000. Profiling measurements conducted over a period of one week. Long term monitoring instruments installed 2001-01-06. Consult Readme file for detail of data files and formats.

---- Public Summary from Project ---- Most of the snow falling on inland Antarctica drains via large ice streams and floating ice shelves to the sea where it lost by iceberg calving or as melt beneath the shelves. Ocean interaction beneath the shelves is complicated, and regions of basal refreezing as well as melt occur. These processes are important not only because they are a major component of the Antarctic mass budget, but because they also modify the characteristics of the ocean, influencing the formation of Antarctic Bottom Water which plays a major role in the global ocean circulation. The processes are sensitive to climate change, and shifts in ocean temperature or circulation near Antarctica could lead to the disappearance of all Antarctic ice shelves. The Amery Ice Shelf is the major embayed shelf in East Antarctica, and the subject of considerable previous ANARE investigation. Ocean interaction processes occurring beneath the shelf are only poorly understood, and this project will directly measure water characteristics and circulation in the cavity underneath the ice shelf, and the rates of melt and freezing on the bottom of the shelf. These measurements will be made through a number of access holes melted through the shelf. The project is closely linked with other projects investigating the circulation and interactions in the open ocean to the north of the shelf, and studies of the ice shelf flow and mass budget. There will be child records for each of the following data sets: AM01 and AM01 b boreholes * CTD profiles through water column * CTD annual records at selected depths * Ocean current profiles through water column * Temperature measurements through ice shelf and across ice-water interface * Small ice core samples * 0.5 m sea floor sediment core * Video footage of borehole walls (including marine ice) and sea floor benthos * GPS records of surface tidal motion * Video AM02 borehole * CTD profiles through water column * CTD annual records at selected depths * Borehole diameter caliper profiles * Temperature measurements through ice shelf and across ice-water interface * 1.5 m sea floor sediment core * GPS records (surface elevation, ice motion) AM03 borehole * Aquadopp current meter data * Brancker thermistor data * Caliper data * FSI-CTD profile data * Drilling parameters data * Seabird MicroCAT CTD moorings at three depths in ocean cavity beneath the shelf * Video AM04 borehole * Aquadopp current meter data * Brancker thermistor data * Caliper data * FSI-CTD profile data * Drilling parameters data * Seabird MicroCAT CTD moorings at three depths in ocean cavity beneath the shelf * Video AM05 borehole * Aquadopp current meter data * Caliper data * FSI-CTD profile data * Drilling parameters data * Seabird MicroCAT CTD moorings in ocean cavity beneath the shelf AM06 borehole * Aquadopp current meter data * Caliper data * FSI-CTD profile data * Drilling parameters data * Seabird MicroCAT CTD moorings in ocean cavity beneath the shelf Taken from the 2008-2009 Progress Report: Progress Against Objectives: The work undertaken in the past 12 months has continued to relate chiefly to the first of our objectives - "quantify the characteristics and circulation of ocean water in the cavity beneath the Amery Ice Shelf". Data from the AMISOR project have provided the first record of a seasonal cycle of ice shelf-ocean interaction. After recovering the 2008 data we now have near-continuous oceanographic data from beneath the Amery at 3 different depths for 6, 6, 3, and 3 years from 4 different sites. Note that the instruments at AM01 and AM02 (6 annual cycles of data each) are no longer recording due to expiration of the onboard batteries (3-5 years expected life cycle). This allows us to investigate the "real" 3-D, seasonally varying, circulation and melt/freezing cycle beneath an ice shelf - rather than the steady state, simplified "2-D ice pump circulation" that has mostly been assumed previously. As much as 80% of the continental ice that flows into the Amery Ice Shelf from the Lambert Glacier basin is lost as basal melt melt beneath the southern part of the shelf, but a considerable amount of ice is also frozen onto the base in the north-western part of the shelf. These processes of melt and refreezing are due to a pattern of water circulation beneath the ice shelf which is driven by sea ice formation outside the front of the shelf. Our multi-year data from 4 sites beneath the Amery ice shelf show that there is a very strong seasonal cycle in the characteristics of the ocean water beneath the shelf, and strong interseasonal variability in this. The seasonal cycle is driven mostly by the seasonal cycle of sea ice formation and decay in Prydz Bay, and interseasonal variations are due to differences in the general ocean circulation, and in particular the upwelling of Circumpolar Deep Water onto the continental shelf in Prydz Bay. The melt and freeze processes beneath the ice shelf, also themselves modify the water characteristics. Taken from the 2009-2010 Progress Report: The AMISOR project drilled two new 600 m deep boreholes on the Amery Ice Shelf in 2009-10: the first on the marine ice flowline to enhance understanding of the re-freezing process beneath the shelf; and the second in a region of known interest with respect to circulation patterns in the ocean cavity below the shelf. Instrument deployments at both sites should provide valuable annual cycle data over the next 4-5 years.

AM01b borehole drilled mid-December 2003. Profiling measurements conducted over a period of a few days. Video recording of borehole walls and sea floor benthos. Sediment sample collected from sea floor. No long term monitoring instruments installed. AM01b borehole was drilled within a few hundred metres of where the ice shelf had carried the original AM01 borehole to, in the intervening 2 years. As the AM01 borehole had a mooring suite of instruments, none were emplaced in the AM01b borehole. There are several video files attached to this metadata record, and further details about them are provided in the accompanying readme document. The data file contains downcam video, sidecam video and miscellaneous video.