Performance of AUSGeoid09 in mountainous regions

Sussanna, Vittorio and Janssen, Volker and Gibbings, Peter (2017) Performance of AUSGeoid09 in mountainous regions. In: 22nd Association of Public Authority Surveyors Conference (APAS2017) , 20-22 March 2017, Shoal Bay, New South Wales, Australia.

Abstract

The Australian Height Datum (AHD) is our current national vertical datum, and AUSGeoid09 is the current quasigeoid model used to compute (normal-orthometric) AHD heights from Global Navigation Satellite System (GNSS) derived ellipsoidal heights given in the Geocentric Datum of Australia 1994 (GDA94). While previous studies have evaluated the AUSGeoid09 model across Australia, these have generally not focused on mountainous regions in particular. This paper investigates the performance of AUSGeoid09 in the Mid Hunter and Snowy Mountains regions of New South Wales, from a user’s perspective. Comparisons are undertaken in an absolute sense (i.e. single point) and relative sense (i.e. height difference between two points) between AUSGeoid09-derived heights and official AHD heights on public record. The performance of AUSGeoid09 is evaluated relative to its predecessor AUSGeoid98. In both study areas, an overall improvement is evident when applying AUSGeoid09 to compute AHD heights. However, a slope was detected for AUSGeoid09 residuals in the Snowy Mountains, and it appears that the geometric component may have overcompensated for sea surface topography in this area. AUSGeoid09 generally provided AHD height differences at the ±0.05 m to ±0.09 m level (1 sigma) and substantially increased the percentage of GNSS-derived height differences meeting third-order differential levelling specifications. This is a very encouraging result, considering the difficulties of spirit levelling in mountainous terrain and the increasing popularity of GNSS-based height transfer in practice. However, it has been shown that some discrepancies still remain between AUSGeoid09-derived heights and AHD. It is anticipated that the new AUSGeoid2020 (to be used in conjunction with GDA2020 ellipsoidal heights) will substantially improve access to AHD via GNSS techniques. The methodology presented in this paper will be very beneficial in regards to future testing of AUSGeoid2020.


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Item Type: Conference or Workshop Item (Commonwealth Reporting Category E) (Paper)
Refereed: No
Item Status: Live Archive
Additional Information: © 2017 Association of Public Authority Surveyors New South Wales Inc.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Date Deposited: 29 Nov 2017 03:26
Last Modified: 30 May 2018 04:52
Uncontrolled Keywords: AUSGeoid09, AHD, geoid model, N values, GNSS, national datums
Fields of Research : 04 Earth Sciences > 0499 Other Earth Sciences > 049999 Earth Sciences not elsewhere classified
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970112 Expanding Knowledge in Built Environment and Design
URI: http://eprints.usq.edu.au/id/eprint/31101

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