1 National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK. maarten.heijnen@noc.ac.uk.
2 Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, European Way, Southampton, SO14 3ZH, UK. maarten.heijnen@noc.ac.uk.
3 National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK.
4 Departments of Geography and Earth Sciences, University of Durham, South Road, Durham, DH1 3LE, UK.
5 Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, European Way, Southampton, SO14 3ZH, UK.
6 Department of Geoscience, University of Calgary, T2N 1N4, Calgary, Alberta, Canada.
7 Natural Resources Canada, Geological Survey of Canada, Box 6000, 9860 West Saanich Road, Sidney, BC, Canada.
8 Energy and Environment Institute, University of Hull, Cottingham Road, Hull, HU6 7RX, UK.
9 Earth Sciences, Center for Coastal & Ocean Mapping, University of New Hampshire, 24 Colovos Road, Durham, NC, USA.