CHS_LSSL_Galway2016 North_Atlantic_HFX_Tromso

Geographic bathymetric grid data at 100 m x 100 m pixel resolution.

Datum: WGS84

Collaboration of Canada, the United States of America and the European Union as part of the Atlantic Ocean Research Alliance's fifth project under the Galway Statement. Project mapped the North Atlantic seafloor along a transect from Halifax, Canada to Tromsø, Norway to further the understanding of marine habitats, conservation and navigation.

Chief Scientist / Primary Investigator name: Paola Travaglini

Platform: CCGS Louis S. St- Laurent (Canadian heavy icebreaker)

Device 1 type: Multibeam echo-sounder (sonar)

Device 1 manufacturer: Kongsberg

Device 1 model: EM122 behind an ice protection window

Data and Data format:

100 m resolution grid of bathymetry

BAG format: Bathymetric Attributed Grid Object

Navigation and positioning:

 Trimble GNSS receiver + antennae

 Applanix POS/MV v5 inertial measuring system

 Horizontal Datum: WGS84 (G1762)

Tidal correction:

Zero tide applied: tides are not well known for the major part of the data and tides over very deep water are generally negligible.

Sound Velocity Profile measurements:

In-situ sound velocity profiles were applied.

Note on accuracy/S-44 survey standards:

Considering the intended output from this survey (IHO Order 1a - Areas shallower than 100 metres where under-keel clearance is less critical but features of concern to surface shipping may exist.) and using an average depth of 2000 m as ‘d’ in the IHO Standard Equation - the allowable Total Vertical Uncertainty (TVU) must be < 26m which indeed the data has achieved (by comparison with overlapping datasets from other surveys/agency data).

IHO Order 1a

Horizontal positioning accuracy: 5.0 m + 5% of depth (95% Confidence level)(~105 m at a mean depth of 2000 m)

Vertical positioning accuracy: 2.5 m < 26.0 m = Sqrt((0.5 m)^2+(0.013 x 2000 m)^2)