Heights in Canada are defined in the system of orthometric heights, according to a method proposed by Helmert in 1890. However, much development in the theory of heights has been done since then, leading to a more rigorous definition of orthometric heights. The new definition takes into account the effects of terrain roughness, laterally varying anomalous topographical density, and the NT geoid-generated gravity disturbance, which are not considered in the Helmert method. This paper presents a calculation of corrections to Helmert orthometric heights, to update them to the more rigorous definition. The corrections for each effect, as well as a total correction comprising all three effects, are evaluated for a Canadian test area which includes several types of terrain. The correction is found to reach decimetres in some mountainous areas.
|Number of pages||9|
|Publication status||Published - 12 Dec 2005|
ASJC Scopus subject areas
- Geography, Planning and Development
- Earth-Surface Processes