IN2023_V07 Southern Ocean Bathymetry 5m - 210m Multi-resolution AusSeabed products

Brief description

This layer group describes multibeam echosounder data collected on RV Investigator voyage IN2023_V07 titled "FOCUS – Fine-scale Observations of the ACC Under SWOT". The voyage took place between November 15 and December 20, 2023, departing from Hobart (TAS) and arriving in Hobart (TAS).

The purpose of this voyage was to significantly improve our capability to observe and understand the impact of small-scale (10-100 km) motions on dynamics of the Antarctic Circumpolar Current (ACC). The novel Surface Water Ocean Topography (SWOT) satellite mission aimed to provide, for the first time, measurements of sea surface height along a broad swath, with spatial resolution at least 10X better than traditional altimeters. While SWOT provided unprecedented spatial and temporal coverage, in situ subsurface ocean measurements were essential to validate the satellite observations and to determine the relationship between small-scale variability in sea surface height and subsurface ocean circulation and dynamics.

This dataset is published with the permission of CSIRO. Not to be used for navigational purposes.

The dataset contains bathymetry grids of 5m to 210m resolution of the Southern Ocean produced from the processed EM122 and EM710 bathymetry data.
Lineage: Multibeam data was logged from the EM’s in Kongsberg’s proprietary *.all format and was converted to be processed within CARIS HIPS and SIPS version 11.4.30. Data were imported into the HIPS project using EM Height and the vessel file appropriate for either the EM122 or EM710. GPS tide was computed using the EGM2008 model EGM_2008_1Min_Aust_WGS84.csar. TPU values were computed using Measured Sound Velocity = 0.5 and Surface Sound Velocity = 0.2. The raw files were analysed for noise and cleaned manually. The data was then gridded at multiple resolutions in python Caris batch script using a Depth filter Vs Resolution guideline derived from AusSeabed Multibeam guidelines v2 and further inspected for outliers. Final raster products are available in L3 folder of this collection. Final processed data were also exported per line as GSF and ASCII format and available in the L2 folder of this collection.

Due to the quality of the GNSS height data coming from the PosMV some of the multibeam lines in the Caris project had Seapath position and motion applied. This information is contained within the multibeam processing log that is available on request.

The data was then gridded at multiple resolutions in python Caris batch script using a Depth filter Vs Resolution guideline derived from AusSeabed Multibeam guidelines v2 and further inspected for outliers. Final raster products are available in L3 folder of this collection. Final processed data were also exported per line as GSF and ASCII format and available in the L2 folder of this collection.