Akademik Veri Yönetim Sistemi
International Workshop on Multi-observations andInterpretations of Tibet, Xinjiang and Siberia (TibXS), Dali, Çin, 10 - 12 Ağustos 2023, ss.1
In physical geodesy and geophysics, gravity anomalies are sometimes required to be downward continued from observations carried on the Earth surface and must be gridded for practical evaluations of Stokes or Newtonian type of integral formulas. The classical determination of the geoid is one of these examples in which this procedure must be applied. In common practice, the analytic continuation of surface gravity anomalies is implemented by the combination of free-air reduction and the removal of constant density plate model for Bouguer reduction. The Bouguer anomaly on the geoid is more appropriate to interpolate gravity anomalies on grid points because of the less dependency of the reduced anomaly values to the topography. However, over mountainous areas final gridded anomalies are significantly affected by observation errors and model assumptions such as approximated gradient of normal gravity, terrain corrections, density model of topographical masses above the geoid. We investigate the gridding effects of surface anomalies in situ gravity observations over two sophisticated topographies, Konya Closed Basin that covers Central Anatolian Plateau and Taurus Mountains in Turkey and Auvergne test area extending into the Alps in France. The various strategies of terrain correction (simple or completed) and density assumptions based on lateral density models are considered to observe the correlation of gravity anomalies with topography. And to be able to study error propagation of interpolation least squares collocation has been used to filter noise in the input data set and extract signals as their associated stochastic properties. The numerical results show that the predicted values are highly dependent on the distribution of surface gravity anomalies over the topography. Besides the statistics of show relatively low rms values of 1-2 mGal for error propagation, the differences between various interpolation methods may exceed tens of mGals, that restrict the accuracy of regional geoid models over mountainous areas.