|Title||Towards the Canadian Geodetic Vertical Datum of 2013 (CGVD2013)|
|Author||Véronneau, M; Huang, J|
|Source||2013 Joint Scientific Congress of the CMOS, CGU and CWRA, abstracts; 2013 p. 1|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20120444|
|Meeting||2013 Joint Scientific Congress of the CMOS, CGU and CWRA; Saskatoon; CA; May 26-30, 2013|
|Subjects||geophysics; remote sensing; satellite imagery; satellite geodesy|
|Program||Geodetic Survey, Canadian Spatial Reference System|
|Abstract||For more than a century, the levelling technique has been serving well Canada in realizing and maintaining its vertical datum through a network of some 90,000 benchmarks anchored to the ground and
stable structures. Despite this large number of benchmarks, the coverage remains fairly sparse in southern Canada and basically inexistent in northern Canada. A substantial number of these benchmarks have disappeared or can be considered unstable.
Nevertheless levelling remains the most precise technique to determine height differences locally. However, it is inefficient and costly when surveying a country as large as Canada. Global Navigation Satellite Systems such as GPS offer an efficient
and precise alternative for height determination at any location globally. These heights are referenced to an ellipsoid, which is a simple mathematical representation of the Earth that, unfortunately, does not provide meaningful elevations. A geoid
model, the separation between the ellipsoid and the geoid, allows the transformation from these ellipsoidal heights to orthometric heights that are compatible with levelling-derived heights and referenced to the mean sea level. With the introduction
of the Canadian Geodetic Vertical Datum of 2013 (CGVD2013) in November, Canada will now define its geodetic vertical datum by an equipotential surface (geoid) and realize it by a geoid model covering entirely North America (land, lakes and oceans).
This modernization of the geodetic vertical datum will replace the levelling- and benchmark-construct CGVD28. The presentation will give a status of the Height Modernization project including definition of the new datum, technical development in
progress, difference between old and new datums, and feedback on the promotion of CGVD2013 through webinars.|
|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, using an innovative approach, the geoid. Geoid modelling is profoundly reliant on the synthesis of gravity measurements of many types. This presentation will provide a status of the project: Agreement between Canada and USA on a
common reference surface, technical development of the geoid model and feedback received on the promotion of the up-coming datum through webinars.