VORF Bringing Land Sea Together Datums are an

VORF, Bringing Land Sea Together • • Datums are an essential component of any SDI/MSDI. Vertical Offshore Reference Frame, 2005 Joint Project with University College London (UCL) Delivers seamless gridded vertical separation data to allow land sea data to be joined and integrated. • Horizontal Data to WGS 84 is complete • VORF methodology: – Satellite altimetry in open ocean – OSGM 05 geoid model (UK) – Tide Gauge data for UK OGC ® Copyright © 2017 Open Geospatial Consortium

Methodology Satellite altimetry Tide gauge data Tidal modelling GNSS observations Plus gravimetric geoid, OSGM 02 datum correction model, UKHO meta-data, coastline polygons, river polygons, etc. OGC ®

Integration of datums – UK & Ireland • Heights with respect to ETRF 89 datum across UK and Irish waters • Heights of all land datums in the British Isles, within the coastal zone – 17 of them. • Heights of Chart Datum, LAT, MLWS, MSL, MHWS, HAT (All used in marine charting). Unifies heights, elevations and depths. OGC ®

The Way Forward • Many Coastal states have developed their own VORF-like solutions • Harmonisation between member states • Updating – new geoid, better tidal measurements, better altimetry. • Distribution and use methodologies. OGC ® Copyright © 2016 Open Geospatial Consortium