CORRECTION TO HELMERT'S ORTHOMETRIC HEIGHT DUE TO ACTUAL LATERAL VARIATION OF TOPOGRAPHICAL DENSITY

Abstract

Helmert (1890) used Poincaré-Prey's gravity gradient for the definition of the orthometric height. According to this approach the gravity value needed for the evaluation of the height is obtained from the observed gravity at the earth surface reduced to the mid-point between the earth surface and the geoid, considering that the gravity gradient is con-stant along the plumbline. Moreover, the mean topographical density p. = 2.67 g.cm -3 is assumed to approximate the actual distribution of topographical density. The correction to Helmert's orthometric height due to the lateral variation of topographical density has been introduced by Vaníček et al. (1995). In this paper, some numerical aspects of this correction are investigated.

Keywords

• Gravity gradient
• orthometric height
• topographical density