Maintaining a National Geoid-Based Vertical Datum

English Abstract:

In November 2013, Canada established the Canadian Geodetic Vertical Datum of 2013 (CGVD2013). This new datum is defined by an equipotential surface (W_o =62,636,856 m²/s²) and realized by a geoid model (CGG2013), making it compatible with Global Navigation Satellite Systems (GNSS) for positioning. The adoption of CGVD2013 represents a major shift from the old datum CGVD28, which was defined by the mean sea level at selected tide gauges and realised by traditional levelling measurements, and a major impact for the users, who have relied on benchmarks for the last 100 years to conduct their surveys.

The presentation will not only discuss the advantages for Canada to moving to a geoid-based datum, but also discuss the challenges in maintaining such as vertical datum in an era where technology is moving rapidly and data are coming in in large numbers allowing the possibility of a quick turnaround in the release of new realisations of the geoid-based vertical datum. This is quite different as when benchmarks were re-surveyed at a 20- to 30-year cycle or sometime never revisited again, keeping heights very consistent over the years. How to satisfy users who want to live in world as static as possible, but simultaneously providing continuous improvement in the vertical datum to satisfy utmost scientific requirements.