From Discrete Gravity Survey Data to a High-resolution Gravity Field Representation in the Nordic-Baltic Region

ABSTRACT

The deduction of a regularly spaced gravity anomaly grid from scattered survey data is studied, addressing mainly two aspects: reduction of gravity to anomalies and subsequent interpolation by various methods. The problem is illustrated in a heterogeneous study area and contrasting test areas including mountains, low terrains, and a marine area. Provided with realistic error estimates, Least Squares Collocation interpolation of Residual Terrain Model anomalies yields the highest quality gravity grid. In most cases, the Bouguer reduction and other interpolation methods tested are equally viable. However, spline-based interpolation should be avoided in marine areas with trackwise survey data.

KEYWORDS:

• Bouguer anomaly
• gravity database
• gridding
• interpolation
• Nordic Geodetic Commission (NKG)
• regional geoid
• residual gravity anomaly
• Residual Terrain Model (RTM) anomaly

Acknowledgements

The Nordic Geodetic Commission (NKG) is thanked for making this study possible. Besides the affiliations of the authors of this contribution, the National Land Service under the Ministry of Agriculture in Lithuania, the Danish Geodata Agency, the Geological Survey of Norway and the Estonian University of Life Sciences are explicitly acknowledged for their data contributions. Some of the authors have been co-financed by a Connecting Europe Facility (CEF) project ‘FAMOS (Finalising Surveys for the Baltic Motorways of the Sea) Odin’ (VEU16013). The figures of this contribution have been generated using GMT (Wessel et al. 2013). Two anonymous reviewers and the editor are thanked for their constructive comments on the manuscript.