Abstract:
This dataset contains the data from Voyage 7.2 1989-90 of the Aurora Australis. The observations were taken from around Heard Island between May and June 1990. The objective of the zooplankton program was to determine the composition, distribution and abundance of zooplankton with the Heard Island-Kerguelen area, thus providing information of food availability to planktivorous fish. Surveys of krill and other zooplankton were made to obtain species identity and abundance data, length and age. Euphausia valentini and Themisto gaudichaudi were found to be the dominant species in the region. Other major species included the euphausiid Thysanoessa, the copepod Rhincalanus gigas and chaetognaths of the genus Sagitta. This dataset is a subset of the full cruise.
Quality
Data were derived from the digitising of plans resulting from a detail survey by G. Crispo, December 1985.
Plans digitised: Plan 3322/003 Sheets 1 - 17 Plan 3322/004 Plan 3322/005
Plan 3322/006 was not digitised because it was compiled from Plan 3322/003 Sheets 1 - 17. Plan 3322/007 was not digitised because a digital version of the survey ... traverse was generated using an alternative method.
The coordinates of one point of the traverse (Mawson's BM) and distances and bearings on the plan were used to calculate a set of coordinates for the traverse. The route was then generated from the traverse coordinates
There were no field notes or reports associated with the plans, therefore the accuracy of the survey is unknown.
Digitising was performed 'heads up' that is the sheets were scanned and then digitised on screen. The estimated accuracy of the digitising was +/- 0.2 metres for the 1:200 plans and +/- 0.5 metres for the 1:500 plans. Each sheet was digitised individually and georeferenced. The sheets were edge matched. Where there was a discrepancy the mean was taken eg., the left and right contour edge were meaned and joined at the mean point.
Data was converted from DWG/DXF format to ArcInfo coverage format. The coverages were generated as specified by the Australian Antarctic Spatial Data Model. Routine AML programs were used to verify the correctness of the contour attributes. Standard data errors (over shoots, under shoots, etc.) were identified and resolved using standard processing techniques. Visual checks were also performed to ensure the correctness of the data. In addition, a graticule coverage was created to check the spatial position of the data.
The survey traverse was not used to coordinate the data. As only one common point could be compared between the two data sets, a verification could not be performed. The survey traverse was based on arbitrary coordinates.
The JMR satellite Doppler position fix of the Transit Hut was used to relate the detail survey to WGS84 coordinates. The latitude and longitude values used for the Transit Hut were derived from the Geoscience Australia (previously AUSLIG) geodesy survey control data base. http://www.ga.gov.au/geodesy/antarc/index.jsp Values as listed on the GA web site on 19 June 2001. Latitude: 67 degrees 0' 30.8859' S Longitude: 142 degrees 39' 41.9990' E Height: 7.000 (Not used in detail survey) Datum: The WGS84 datum on which these position are based was derived from Transit Doppler positions and is estimated to have an absolute accuracy of about 2 metres.
Additional information on the orientation of the detail survey and wooden block where the JMR satellite doppler fix was made: Report from John Hyslop (GA 15 November 1995) (Copy in AAD file 00/802 page 31) 'The survey of Cape Denison was based on this mark and it is assumed that true north is through this point. By plot the local survey grid is parallel to the meridian at this point and the position of the hut agrees with these coordinates but the latitude of the topo map is wrong. It should be S 67 degrees 00' 00' and not S67 degrees 69' 00'.' The topo map referred to is the historic map of Cape Denison printed in November 1990. GPS coordinates (supplied by Henk Brolsma, Mapping Officer, AAD) were used to check the spatial position of the data with acceptable results. The data set was standardised to conform with the Australian Antarctic Spatial Data Model.
Note 1: Where the 0m contours conflict with the coastline (resulting in negative contour values), the 0m contour has been adopted as the coastline. This only occurs on the southern and eastern parts of Boat Harbour. Comment by G. Crispo on the accuracy of his 1985 survey (Copy in the AAD file 00/802 page 20): 'Most of the plans are okay but a contour interval of 1 metre instead of 0.5 metres for the 1:500 scale plans would agree more with the accuracy of the field work. The 0.5 metre contour interval for the 1:200 plans is okay. Contours of the seabed in Boat Harbour should be omitted as the accuracy of the 'soundings' is questionable.' View entire text
Note 2: Some years after plans 3322/003 sheets 1-17 were digitised, copies of Cripso's survey field notes were received. These were scanned in 2007.
The original large plans drawn by Cripso as part of this work were unfortunately lost by a contractor, but copies of these plans are held at the Australian Antarctic Data Centre (see Access Constraints).
Access Constraints
Stored data format: ArcView shapefile Available format type: ArcView shapefile. Stored as geographicals.
A pdf scanned copy of the notes taken in the field are available for download from the URL given below. The original copies of the field notes are stored in the office of the Mapping Officer at the Australian Antarctic Data Centre in the Australian Antarctic Division.
Copies of the large plans drawn by Crispo are available in the Australian Antarctic Data Centre Map Store.
Usually mapped to a Universal Transverse Mercator projection, Zone 54.
Please follow instructions listed in the citation reference at the provided URL when using these data.
This
"Cape Denison Detail Survey, December 1985, GIS Dataset" is licensed under a Creative Commons Attribution 3.0 Unported License.
