2010/11 VMS - Bathymetric Data ProcessingEntry ID: VMS_Bathy_Processing
Abstract: Passage sounding data collected by Aurora Australis 2007-2011 was processed from the 12KHz EDO 323HP echo sounder.
All voyage data sets were processed in the following manner. As the Aurora Australis sails from either Hobart, Tasmania or Fremantle, Western Australia all the shallow water data files containing depths less then 200m around these ports were not processed and deleted. If the sea ... floor image was too hard to determine during the voyage either parts of day lines were not processed or the whole line deleted depending on the quality of the data. This is evident with some day *.CSV files containing a second or third file, these files had the same file name and were given a end character of _2 or _3. Unfortunately the program Echoview is meant to allow the user to span gaps when processing a line but more often than not, this was not the case. So if there was a requirement to a have gap in the daily file then usually a second file was created. Regularly throughout all voyages files were observed that had no GPS data associated with the depths. Any raw files without GPS data could not be processed, all these files have been deleted. Occasionally corrupt files were experienced, and these corrupt files have also been deleted. When the Aurora Australis was at anchor off an Antarctic Station these files too were deleted. With the various problems with the raw data files, no voyage has complete sounding data for the whole voyage. Some voyages have large sections of data missing, but unfortunately this data was not able to processed due to one of the above factors.
All soundings were processed utilising the spheroid, WGS84 and only geographic co-ordinates have been determined. UTM grid co-ordinates were not calculated during the processing stages due to software limitations. Grid co-ordinates were not calculated for the final HTF files.
Scripts were developed to apply depth water corrections, tide offsets if shallower than 200m of water and the layback of the sounder with respect to the Ashtech GPS.
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Start Date: 2011-01-04Stop Date: 2011-02-06
ISO Topic Category
Quality The Ashtech GPS unit is not currently licensed to receive differential corrections and the AAD are not aware when they last paid for the annual subscription. A error value still exists for the Transducer/GPS offset, even after the script correction. A 5m error value has been applied in the horizontal accuracy calculation spreadsheet for this correction. The best assessment of the horizontal accuracy is therefore Order 2.
Access Constraints These data are not available for general use until the report has been cleared by the Australian Navy Hydrographic Office.
Use Constraints This data set conforms to the PICCCBY Attribution License
Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=VMS_Bath... when using these data.
Data Set Progress
Role: TECHNICAL CONTACT
Phone: +61 3 6232 3586
Fax: +61 3 6232 3351
Email: ben.walter at defence.gov.au
Australian Antarctic Division 203 Channel Highway
Province or State: Tasmania
Postal Code: 7050
Role: DIF AUTHOR
Phone: +61 3 6232 5062
Email: dave.watts at csiro.au
CSIRO Marine and Atmospheric Research Castray Esplanade
Province or State: Tasmania
Postal Code: 7000
Creation and Review Dates
DIF Creation Date: 2011-05-18
Last DIF Revision Date: 2011-05-23