HYDRO 2016 Paper 5A1
Stefan Wiehle, Bernat Martinez, Knut Hartmann, Martin Verlaan, Tim Thornton, Simon Lewis, Dick Schaap
The project "BAthymetry SErvice platform" (BASE-platform) addresses the lack of available up-to-date, high-resolution bathymetry data in many areas of the world. With the increasing number of earth observation satellites, e.g. by the ongoing deployment of ESAs Sentinel fleet, remote sensing data of the oceans is widely available. BASE-platform's ambition is to use this data for creating bathymetric maps and supply them to end users.
Three sources of satellite information are combined in BASE-platform: optical, SAR and altimetry data. From optical satellite images, the water depth can be obtained by analysing the spectral changes of the seafloor. This method works in optically shallow waters only, where the seafloor contributes a detectable part of the measured signal. Farther from the coast, SAR bathymetry is used which detects changes of wave lengths in the ocean, indicating changes of the underlying bathymetry due to the shoaling effect. Information about deeper areas is then acquired from altimetry data. Altimetry satellites use radar signals to determine the height of the ocean surface below them. Changes in the bathymetry cause gravimetric distortions which influence the height of the sea surface; this allows a reproduction of underlying bathymetric features.
Additional input is gathered from crowd sourced data, providing depth information from a large number of ships and small craft along their regular tracks. These in situ measurements are also used for the calibration of EO data. With tidal modelling, all data are corrected for the tides during their respective acquisition time. By combining all these sources, a merged bathymetry product can then be created.
A major point of BASE-platform is the distribution to the user by a bathymetry data portal, where data will be available off-the-shelf as well as on demand. Adequate metadata will be provided along with the bathymetry so usability by the end user is ensured.