British Geological Survey (BGS) Geophysical and Multibeam Survey 2005/4: Summer Isles / East Minch (04/Jul/2005 to 23/Jul/2005)

Geophysical equipment types used included: Surface Tow Boomer. The survey was undertaken by British Geological Survey. NAVIGATION: Differential GPS, all position data are referred to the WGS 84 datum. For the swath bathymetry survey the DGPS receiver was supplied by Fathoms and input directly to the Geoswath system. For the surface tow boomer operations the ship’s DGPS system was used. SURFACE TOW BOOMER:Source: EG&G plate in Applied Acoustics catamaran. High Voltage Power Supply: 2 x Applied Acoustic Engineering CSP3000 capacitor charging units, (1 plus a spare). This unit was powered from the ship’s mains and with a switchable output up to a maximum of 2.2 KJ, maximum used for the S.T.Boomer was 300J at a repetition interval of 0.3 seconds. Hydrophone: 2 x Teledyne, 10 m, 7 channels with all summed to give a single output, (1 plus a spare). The summing amplifier used was a newly developed BGS unit, which also included low pass and anti-alias filters. The new unit proved to be significantly less noisy than the previous version, a feature which was particularly noticeable in deep water when very high gain levels were required. Recording: CODA DA200 four channel digital recording and processing system, with the data being recorded on harddisk in CODA format and backup to Exabyte tape in both SEGY and CODA formats. The data were recorded with a sampling frequency of 12kHz, record length of 200mseconds and a bandpass filter of 450-4500Hz. The start of recording was delayed in deep water to maximise the usable data record below the sea bed. Position was recorded with every shot. On-line processing: CODA system. SWATH BATHYMETRY: Geoacoustics GeoSwath system, contractor Fathoms Ltd. A TSS DMS25 Motion Sensor, a mini-SV probe and a Tritech single beam echosounder, to measure the depth directly below the transducers, were all mounted in the transducer head assembly. Additionally, input from a gyrocompass and differential GPS were also required and these were supplied by a TSS Meridian gyrocompass and a Trimble DGPS receiver. All positions were corrected to the transducer location so that the processed bathymetry data was correctly located. Data processing: Fathoms personnel used a GeoSwath Plus processing package on a second PC. Bathymetry data is in UTM zone 30N and the backscatter was in UTM zone 29N. Backscatter data: ARCGRID; TIF images. Fledermaus (.sd) available on request. For more detailed information on the acquisition equipment and data collection techniques, operational standards, data processing methods and quality control procedures used on this survey see the Report of Survey/Cruise Report and associated documentation where available. The information available may vary depending on the age of the survey. Data are checked and loaded to the BGS Coastal and Marine data management system following BGS marine data management procedures.

Minimal Distance: 5 urn:ogc:def:uom:EPSG::9001

INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of unknown theme