This dataset contains 102 depth measurements of the water column in Long and Tryne fjords, which are in the northern Vestfold Hills, Prydz Bay, Antarctica. Sea ice thickness and snow thickness were recorded simultaneously. The motivation for this project has been to yield a description of the pupping and moulting habitat of Weddell seals. This information will assist the interpretation of 25+ years of data on seal distribution within that area. Our data were collected between 7th and 13th December 1999. The measurement sites were chosen according to geographical features; their exact location was determined by GPS with an accuracy of about 25m. At each site a 5cm diameter hole was drilled through the sea ice and a weighted measurement tape was lowered through the ice-hole to the bottom. Water depths were measured to the nearest centimetre; ice and snow thicknesses were measured to the nearest millimetre. A minimum depth of less than 3m was found in a narrow channel between small islands immediately west of Shirokaya Bay. The maximum depth of the water column was 222m in the middle basin of Long Fjord. The tidal range for the measured days was less than 0.5m, with tidal corrections applied to the raw data. Water samples were taken in Breid Basin and the middle basin of Long Fjord. These and water samples taken in Snezhnyy Bay [pers. comm. J. Laybourn-Parry, 1999] show aerobic and relatively fresh water for all upper basins. This indicates that even the far basins of both fjords are well mixed despite the drainage of large volumes meltwater from the Antarctic plateau into the fjords. See related URL for data and a spatial summary of the data. See Entry: long_tryne_bathy for an interpolation of bathymetry made using the Topogrid command within the ArcInfo GIS software, version 8.0.2. Coastline and spot height (heights above sea level) data, extracted from the Australian Antarctic Data Centre's Vestfold Hills topographic GIS dataset (see Entry: vest_hills_gis), was also used as input data to optimise the interpolation close to the coastline. The fields in this dataset are: day weighpoint lat(dd) long(dd) ice (cm) freeboard(cm) snow(cm) depth(m)

Metadata record for data from ASAC Project 1342 See the link below for public details on this project. ---- Public Summary from Project ---- This project involves field trialling of software written as part of ASAC project 1212 (2000-2001) to determine sea-ice thickness in real-time from ship-borne electromagnetic induction measurements. Computer simulation of ship- and helicopter-borne electromagnetic induction measurements over realistic sea-ice structures will also be performed in order to assess the suitability and cost-effectiveness of helicopter-mounted systems for future Antarctic sea-ice thickness measurements. Equipment used in this study were the IBEO PS100 infrared laser altimeter and the Geonics EM31 geophysical electromagnetic induction device. The fields in this dataset are: DAY is Julian day TIME is in seconds after midnight (UTC). LASER is the laser altitude above the snow/ice (metres). A zero reading indicates no return (open water). PITCH is pitch of the system in degrees. ROLL is roll of the system in degrees. COND-A is analogue conductivity from the EM31 (not used). PHASE-A is analogue in-phase response from the EM31 (not used). COND is the estimated depth to seawater (metres) from the EM31-ICE processing module. PHASE is the EM31 in-phase response (expressed as parts per thousand of the primary field). A value of 9.99 indicates the magnetic field was too large to be recorded. SITE LATITUDE LONGITUDE SNOW THICKNESS ICE THICKNESS FREEBOARD a is the electrode spacing. R is the measured resistance. Rho is the apparent conductivity (not true conductivity) = 2 aR. CONDUCTIVITY = 1/Rho.