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TitleAdjustments of the Canadian levelling networks in CGVD2013
AuthorVéronneau, M; Huang, J
Source2013 Joint Scientific Congress of the CMOS, CGU and CWRA, abstracts; 2013 p. 1
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20120443
Meeting2013 Joint Scientific Congress of the CMOS, CGU and CWRA; Saskatoon; CA; May 26-30, 2013
Mediaon-line; digital
File formathtml
Subjectsgeophysics; remote sensing; satellite geodesy; satellite imagery
ProgramGeodetic Survey, Canadian Spatial Reference System
AbstractCanada is moving to the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which will be realized by a geoid model, by November 2013. During the transition period a large number of stakeholders will continue using benchmarks across Canada, so each benchmark will be published with a new elevation integrated into CGVD2013. The old elevations in CGVD28 will continue to be published along with the new elevations. Prior to CGVD2013, scientific geoid models developed at Natural Resources Canada were constrained to geoid heights representing the separation between the ellipsoid and CGVD28, creating hybrid geoid models that fit to CGVD28. Now, the reverse procedure is applied, i.e., the adjustment of levelling network is constrained to a series of orthometric heights determined from accurate GPS ellipsoidal heights and a geoid model, adjusting the heights of the benchmarks to CGVD2013. In this study, we have conducted a number of experimental adjustments of the levelling networks (Continental, Vancouver Island, Prince Edward Island, Newfoundland, etc.) by making use of Canadian Gravimetric Geoid Model of 2010, which is shifted to represent the Canada-USA agreed reference surface. The adjustments include a minimum-constraint solution and a series of multi-constraint solutions at selected stations forming the Canadian Active Control System (CACS) and Canadian Base Network (CBN). The adjustments differ also by the procedure: 1) include all levelling observations in a single adjustment; or 2) include levelling observations by epochs in a step by step approach. The adjustments also include a crustal motion correction to the levelling legacy data from a GPS-derived vertical velocity model. The new adjustments must remove the distortion in CGVD28, but maintain the high precision of the levelling data regionally while confirming to CGG2010 nationally. Each solution is compared to the 2500 'GPS on Benchmarks' stations in Canada to analyze how close each solution is to CGVD1013.
Summary(Plain Language Summary, not published)
NRCan is responsible for the Canadian Spatial Reference System, a national standard that enables high accuracy positioning and geodetic measurements of the dynamic Earth. An essential component of the Canadian Spatial Reference System is the height reference system, enabling determination of heights above sea-level, critical for water management. Modernization of the height reference system will take place in 2013 (CGVD2013), using an innovative approach, the geoid. Geoid modelling is profoundly reliant on the synthesis of gravity measurements of many types. However, still a large number of our stakeholders rely on benchmarks for activities. This research will allow a smooth transition for our more traditional users towards the modernised height system.