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SIPEX

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  • We checked each site by taking ice cores and observing the algae biomass to determine the likelihood of krill living under the sea ice in each location. We also used a Remotely Operated Vehicle (ROV) with cameras attached to observe the abundance of krill under the sea ice. If krill were present we used on the sea ice floe a zooplankton pump, called MASMA, according to Meyer et al. 2009, whereas at the edge of the floe column a custom-built fish pump system was used to collect krill near the surface. The Aqualife Biostream BP40 fish pump was capable of pumping up to 1300 litres per minute without harming animals that pass through the pump. For much of the voyage it was operated from the ctd room and at this increased suction head it ran at about 500 litres per minute. Krill were caught at ice stations 2, 6, 7 and 8. The Krill Sample-Overview.xls file contains information regarding how many krill were caught at each ice stations, who was involved and related information. The SIPEX II Krill Voyage Report.docx contains information about the various issues that were encountered during the voyage. It also contains information from the Bottom Krill experiment, which has its own dataset and metadata record. It is duplicated in both datasets. The larvae were used for a growth experiment using the IGR method and after length measurements frozen for carbon, nitrogen, lipids, stomach and gut content analysis. The total and carapace length were determined of juveniles as well as their digestive gland size. Animals were than dissected and tissues frozen at -80C for further analysis (see above). These condition parameters will be discussed in relation to physical and biological environmental parameters of the ice floe (e.g. sea ice thickness, snow coverage, under ice topography and biomass). When this data is analysed, the dataset will be updated to include analysed versions of the data listed in the Krill Sample-Overview.xls file. Also included in the dataset are technical documents and manuals pertaining to the fish pump that was used. Meyer B et al. 2009. Limnol Oceanogr 54:1595-1614

  • This dataset contains data resulting from the measurement of brine samples extracted from the sea-ice during the 2012 SIPEX 2 (Sea Ice Physics and Ecosystems Experiment) marine science voyage. The Brine was collected from partially drilled holes in the ice using suction. In some of these cases the brine analysed came from holes which correspond to permeability measurements. In these cases a core number is associated with the brine data which will correspond to the core number in the permeability data set found in the master core list Excel file. The purpose of this data set was to act as a first step to quantify the effect that extra cellular carbon may have on the physical properties of brine and sea ice. At least 1 litre of brine was collected from each partial hole for analysis. The total sample was split for the following analyses. Viscosity of the brine was measured before and after filtering out any biological components that may have been in solution or otherwise in order to assess whether or not extracellular carbon has an effect on fluid flow in sea ice. What was not used for viscosity measurements was used for chlorophyll, extra-cellular carbon and bacterial analysis to gain a sense of the level and type of biology and biological compounds in the brine to then be compared to the measured physical properties. The biological analysis will be carried out at the university of Tasmania by Sarah Ugalde. On many of these samples the complex permittivity of the brine was also measured and the data can be found in the Relative_Permitivity_of_Brine folder with each sample corresponding in core number. For info on the permittivity measurements please see the metadata in that folder.

  • This dataset contains sea ice surface brightness temperatures using a portable passive-microwave radiometer operating at 36Ghz-H,V mounted to the undercarriage of a Squirrel helicopter during SIPEX 2, 2012. This radiometer is the same sensor as satellite passive-microwave radiometer AMSR-E and AMSR2. Our passive-microwave radiometer is launched on the same helicopter as Jan Lieser's (RAPPAL), so please see the "SIPEX-2 RAPPLS Surveys (Radar, Aerial Photography, Pyrometer, and Laser Scanning system)" metadata file for details of the aircraft. The RAPPLS dataset also contains track (GPS position) and altitude data, which can be used in conjunction with this dataset. The CSV files in this dataset are the raw files as output by the sensor. These raw data files show only the relevant parameters (time and brightness temperatures).

  • This dataset contains data relating to an experimental method in which sea-ice samples were measured in an S-band microwave waveguide. This was conducted as a part of the 2012 SIPEX 2 (Sea Ice Physics and Ecosystems EXperiment) marine science voyage. A specially designed waveguide apparatus was connected to an Agilent FieldFox Portable Network Analyzer. Small parallelopipeds (7 cm X 3 cm X 1.9 cm) of sea ice were cut with a hand saw in a specially designed jig which holds an initially cylindrical core. The samples were placed at the end of the waveguide, configured to measure the vertical component of the effective complex permittivity tensor, and microwaves of frequency 2.9 GHz were sent down the tube. The samples were sized precisely to fit snugly in the end of the waveguide in order to minimize spurious reflections. The FieldFox recorded the coefficients of the scattering matrix, from which the complex permittivity can be computed. Sample temperature was taken both before and immediately after insertion into the waveguide. In order to assess the presence of off-vertical components of the electromagnetic field and how they may affect the measurements, a second sample was prepared with an orthogonal orientation, adjacent to the first sample. The same microwave measurements were taken on the second sample, to be later correlated with those from the first sample. The samples were stored in the freezer for later crystallographic analysis, and subsequently melted for salinity measurements. Prior to melting the samples were measured using callipers to determine their dimensions precisely. Samples were measured along each face at their minimum and maximum point for their width in the direction of propagation. In most cases samples were measured in all dimensions for better error analysis. A thin vertical section, approximately 5mm thick, was taken from each microwave sample stored for analysis. These sections were placed between a pair of cross polarized plates and photographed. Photos of the crystallography cores can be found in the crystallography folder, in a sub folder titled microwave. Each photo also contains a tag indicating the core number, site taken, date, as well as a V or an H indicating whether the sample was used for measurement of the vertical (V) or off-vertical (H) response. The scattering parameters recorded by the Field Fox can be found in the Data folder. Each file is named according to the microwave core measurement it represents and whether the measurement was of the vertical (V) or off-vertical (H) response. Each contains a standard S11 scattering parameter, stored as a comma separated value (CSV) file. Raw data can be found in the raw folder, and data that has been processed for ease of Matlab import can be found in the Reformatted_for_matlab folder. This processing involves taking output data that by default has four entries in a single column vector and remapping the data to create a four column matrix, each with a single entry. Recorded values for each microwave sample can be found in the Master_Core_List.xls Excel spreadsheet, within the Microwave worksheet. This worksheet was generated directly from notebook data, and contains the date, core number, depth of interface between the two collected samples, the minimum, maximum, and average thickness along the axis of propagation, The recorded temperatures from before and after measurement, the salinity, and calculated brine volume fraction. Finally, the worksheet contains notes, and a column to indicate whether we believe this data is somehow bad. Measurement information for thicknesses along other axis than that of propagation can be found in notes, but this data may at some stage be incorporated into a separate column. Please see the notes section for reasons why a data point was determined invalid. Typically this was due to the corresponding sample breaking while cutting into the parallelepiped shape. Scans of the original notebooks containing measured salinity values, thicknesses, and temperatures from which the Permeability worksheet were created are provided in the notebooks directory.

  • The intention of the Deep Krill Camera and Trap System was to monitor and capture krill found during deep CTD operations. Two traps were installed on the CTD in place of Niskin Bottles. At pre-determined depths an internal light was illuminated and the traps were opened. After a set period of time a second trigger signal was sent to the traps, closing the entry point, encapsulating any Krill that were inside. The Krill Camera system was installed onto the CTD rosette. It consisted of a high-definition video camera (a GoPro Hero 2) within a pressure housing, flanked by two LED light sources. The power for this system was supplied via a rechargeable battery pack also mounted to the CTD. The camera system was remotely controlled from the surface via the CTD communications link. At specific depths the lights and camera were activated, recording the water column and ocean floor by adjusting focus length for fixed durations in an attempt to document Krill at lower depths. An additional camera was introduced into the system, mounted to allow video capture of the Krill Trap Operation. This camera was set to record at the beginning of the operations and left running for the duration of the deployment. Video data from the Krill camera is in MTS format, which can be opened with VLC Media Player. Trap footage is recorded in MP4 format, which can be opened with Quicktime or VLC Media Player. Trap triggering and camera operation data was recorded manually by Rob King.

  • Zooplankton were collected during the winter-spring transition during two cruises of the Aurora Australis: SIPEX in 2007 and SIPEX II in 2012. To determine size and biomass, key species were measured. Measurements of Prosome, Urosome and Total length are provided. The zooplankton were taken from samples collected with umbrella nets, RMT1 net and sea ice cores. They were measured under a Leica M165C steromicroscope using an ocular micrometer. The ocular micrometer was calibrated against a stage micrometer (+/- 0.01 um).

  • Multiple CTD (conductivity, temperature, depth) casts were deployed during the SIPEX II AAD Marine Science voyage in September-November 2012. The system uses a descending rosette capable of holding up to 24 CTD bottles. During this voyage the CTD rosette also housed two krill traps (using controllable lights) and two GoPro cameras contained in pressurised, waterproof containers that were used to monitor the krill traps and view objects both on the sea bed and in the water column. Some functions of the GoPro cameras could be controlled from within the ship using the same transmission cable used by the CTD system. These functions included being able to change the focus setting of the cameras or start/stop recording. More information about the krill traps and cameras is contained in the SIPEX II Bottom Krill dataset. When a bottle is 'fired' from the ship it briefly opens, draws in water samples and closes again. It is not reopened until it is brought on board the ship. Bottles are opened at different depths to obtain samples from these depths. The depths vary from cast to cast and so are recorded in the CTD Log sheets (contained in this dataset as PDF files). Only raw data is contained in this dataset. The raw data was used by a variety of experiments during the SIPEX II voyage to produce results applicable to each experiment. Thanks go to the P and O crew of the RV Aurora Australis for their assistance during CTD operations.

  • Gas Flux over Sea Ice ------------- We observed amount of gas exchange between sea ice and atmosphere. At the ice station, semi-automated chambers developed in Japan, were used for measurement of air-sea ice CO2 flux. These chambers could be used to examine spatial variability and also temporal variability of gas flux over sea ice. Samples were also taken from the snow and ice in order to measure CH4 and VOC, however these analyses will be conducted post-voyage. This metadata record will be updated in future to reflect the analysis. The chambers are designed to be placed over a snow and sea ice. When the lid is closed, CO2 concentration was measured. The opening and closing functions of the chambers are automated and were set to a 30 minutes interval. CO2 concentration (as voltage) were recorded in the data logger (CR10X, Campbell Scientific Inc.) and downloaded after the experiments. Raw data are contained in the excel files. During the CO2 flux measurement, we collected the snow, sea ice, brine/slush and under-ice water. Snow and sea ice samples were melted after sampling in PVDF film bags (like Tedlar bags in order to avoid gas exchange with ambient air) in 4C temperature and treated for analysis. A chemical analysis for carbonate systems and VOC (water), salinity, nutrient, pigment and oxygen isotopic ratio samples will take place in Japan after the voyage for analysis. During the cruise, to examine ice growth processes, we made sea ice thin-section to classify the ice cores into granular ice, columnar ice or mixed granular and columnar ice (Eicken and Lange, 1989). The CO2 data are contained in Excel spreadsheets. These use Japanese column headings. Calcium Carbonate (CACO3.6H20) as Ikaite in Sea Ice and Snow ----------- At each listed ice station we collected sea-ice cores using a Kovacs 9cm ice corer. Cores were sectioned into 10-20cm and melted at 4 degrees C, filtered and dried for later analysis of Calcium Carbonate in a home laboratory using an ICP, which produces text file outputs (included). Also included is a spreadsheet listing the cores, and the calcium carbonate measurements.

  • This dataset contains measurements of nitrate in snow on the sea-ice. These vertical nitrate profiles were collected from snow pits that were dug at each ice station during the SIPEX II voyage in 2012. The snow depths range from 25-55 cm and snow samples were collected in 5 to 10 cm intervals from the snow surface to the top of the sea-ice. The snow was then melted and passed through a resin to collect the nitrate. The nitrate was then eluted with a strong NaCl solution and kept in bottles that were frozen at -20 degrees C. The samples were shipped frozen back to Seattle where they will be analysed using an ion chromatograph. The ion chromatograph outputs the data as text files. At this stage, samples have been collected but not analysed so no data currently exists.

  • Particulate impurities in snow such as dust and soot can absorb sunlight. This is important for snow albedo in the Arctic, but probably not in the Antarctic. Snow was collected in plastic bags through the full depth of the snowpack over first-year sea ice at several locations: one location each on Ice Stations 1, 2, 3, 4, 7, upwind of the ship. The snow was melted and the meltwater filtered. The filters will be analysed for light-absorbing impurities in a laboratory spectrophotometer in Seattle. Samples of size ~1 kg were collected at Ice Station 1. The filters were blank, so at Ice Stations 2 and 3 larger samples of size 2-4 kg were collected. The filters were still blank, so at Ice Stations 4 and 7 larger samples of size ~8 kg were collected; these do show a slight darkening visible by eye. No snow samples were collected at Stations 5 and 6. Local (ship) time is UTC+10; Sun time is UTC+8. Filters are labelled with prefix 'AO' for Antarctic Ocean. This dataset currently contains snow density (except for at one ice station) and volumes of melt water that were filtered. No further analysis has been carried out on these samples at this point, however at a later stage the filters will be analysed for spectral absorption and converted to a mixing ratio of black carbon in the snow.