How Satellite Altimetry Contributes to the Vertical Datum Problem
Michael Sideris(1) and Georgia Fotopoulos(2)
University of Calgary,
2500 University Dr NW,
(2) University of Toronto, 35 St George Street, M5S1A4, Toronto, Canada
Over the past several decades, the definition of a global vertical datum and the realization of such a system has been a topic of great research and debate. Many different methods for defining a vertical reference system to be implemented all over the globe have been presented. The definition of such a global vertical reference system is further complicated by accuracy and spatial coverage limitations with traditional techniques. The purpose of this study is to provide a detailed account of the major efforts conducted over the years for defining a vertical datum in Canada. Both theoretical developments and practical aspects will be discussed, based on research conducted at the University of Calgary over the past ten years. The paper will emphasize the contributions of altimetric satellite measurements to the vertical datum definition issue. The Canadian situation will be studied in the context of existing problems and complications for defining a regional vertical datum, including the expected improvements by the use of data from the new satellite gravity missions. Since one of the major problems with the definition and subsequent acceptance or adoption of a globally defined datum is dealing with existing regional datums, a case study on the status of the Canadian vertical datum will be useful for understanding the topic.