A Refined Adjustment Model for the Secular Change of Gravity on the Fennoscandian 63° Latitude Gravity Line

Abstract

Repeated precise gravity observations along the precise gravity lines in Fennoscan-dia covering the period 1966–1984 were published by Mäkinen et al. (1986). The observations of the most extensively measured gravity line at about latitud 63 were analysed by Ekman et al. (1987), Sjöberg et al. (1988) and Sjöberg (1989). These investigations show that the estimated secular change of gravity, of the order of —0.2 μGal/mm uplift, is very sensitive to the individual weighting of the data. In the present study the adjustment model is refined, e.g. by the inclusion of an iterative weight estimation procedure. Nevertheless, the result is the same as for the simple adjustment: the ratio of estimated change of gravity to land uplift is of the order -0.16 ± 0.04 μGal/mm in agreement with a simple viscous flow model.