Ferry Gravimetry Data from the EU FAMOS project

Within the European Union FAMOS project, GFZ performed two gravimetry campaigns on commercial ferries in the Baltic Sea in 2017 and 2018. The nature of such “non-dedicated” campaigns is different from “dedicated” campaigns which are performed on research vessels with tracks planned according to gravity measurement needs. The non-dedicated campaigns use non-survey vessels (e.g. ferries) or survey vessels running for other purposes (e.g. hydrographic measurements). Measurements conducted on such conditions may require additional corrections besides the typical marine gravimetry corrections. We investigated two additional corrections, namely the vertical accelerations due to the motion of the ferry in the vertical direction and the dynamical effect due to the cross-coupling between horizontal and vertical acceleration components. To assess the usefulness of non-dedicated campaigns, we analysed gravity measurements collected on two commercial ferries and demonstrated that the standard processing without the above mentioned two corrections, as used in dedicated campaigns, already delivers good quality end products that fulfil the requirements of a typical marine gravimetry survey with an uncertainty of about 1 mGal for a much lower cost. Therefore, the data published in this contribution is a product of the same algorithm we use for dedicated campaign measurements. Based on our findings, we suggest that gravimetry campaigns on commercial ferries can be used to complement dedicated marine gravimetry campaigns and contribute to geodetic purposes.