Automated monitoring of CORSnet-NSW using the Bernese software
Haasdyk, J and Roberts, C and Janssen, V, Automated monitoring of CORSnet-NSW using the Bernese software, In: Proceedings of XXIV FIG International Congress: Facing the Challenges - Building the Capacity, 11-16 April 2010, Sydney, Australia, pp. 1-19. (2010) [Non Refereed Conference Paper]
Global Navigation Satellite System (GNSS) observations are increasingly used for a wide
range of applications, and networks of Continuously Operating Reference Stations (CORS)
are being rapidly installed to provide centimetre-level relative positioning. It is becoming
increasingly important to determine and report on the quality control of these installations.
This is necessary for legal traceability of data and measurements as well as for long-term
stability studies of station coordinates.
This paper presents the automation of high-precision daily coordinate solutions of stations in
CORSnet-NSW, using the Bernese software. CORSnet-NSW is a rapidly expanding network
of CORS stations separated by significant distances (up to 275 km in remote regions) in the
state of New South Wales, Australia. Coordinates are obtained in ITRF2005 and transformed
into GDA94. The ongoing analysis of these coordinates can reveal: 1) Site specific velocities
of a network at higher densities than those provided by the IGS network, 2) A medium
density sampling of the local distortions present in the GDA94 datum and the distortions in
ellipsoidal heights derived from the Australian Height Datum 1971 (AHD71) and
AUSGeoid98, and 3) Trends in site coordinates revealing local ground deformation.
GPS data collected over a short period (60 days) in 2009 is sufficient to calculate station
coordinates at millimetre-level precision, and velocities with 2-4 mm/yr precision that agree
with expected tectonic motions. Significant differences are shown to exist between the
coordinates of CORSnet-NSW stations obtained from the Bernese solution and their
published GDA94 and ellipsoidal height coordinates at the 0.2 m and 0.3 m levels
horizontally and vertically, respectively. The published coordinates are calculated from local
tie-surveys and retain local distortions in GDA94 and AHD71 for the benefit of local users.
Network-RTK error modelling methods, legal traceability via national ‘Regulation 13’
position certification, and overlapping CORS networks will soon require station coordinates
in a more homogeneous datum, such as ITRF. Ever-increasing GNSS accuracy will highlight
the local distortions present in GDA94 and AHD71/AUSGeoid98 and cause possible
confusion for users. For these reason the time has come to review and renew the national horizontal and vertical datums.