Offshore Physical Environmental Guidelines
Appendix C – Monitoring Equipment Specifications
Table C-1 - Monitoring Equipment Specifications
| Accuracy Specifications | Collection Specifications[1] | |||
|---|---|---|---|---|
| Sensor | Accuracy | Sensor Requirements | Averaging Intervals | Recording Intervals |
| Wind Speed | ± 1 kt up to 20 kts ± 5% for speed > 20 kts |
- resistance to icing[2] |
1 minute (suggested) 2 minute 10 minute 1 hour (suggested) |
10 minutes (10 minute average, hourly otherwise) |
| Wind Direction | ± 5 degrees | As per wind speed | As per wind speed | As per wind speed |
| Pressure | ± 0.1 hPa (barometer reading) ± 0.2 hPa (sea level pressure[3]) ± 0.01 hPa (QNH altimeter setting) |
- capability to display 3-hour time trace required for tendency characteristic |
Instantaneous | 1 minute |
| Air Temperature | ± 0.1 degrees Celsius | - operation over full temperature range (for region in which equipment used) Suggested: - digital output (real time or archival) capability |
1 minute | 1 minute |
| Humidity (wet bulb) | ± 0.1 degrees Celsius | - operation over full temperature range (for region in which equipment used) Suggested: - digital output (real time or archival) capability |
1 minute | 1 minute |
| Cloud Height | ± 10 m up to 100 m ± 10% from 100 m to 300 m ± 20% for above 300 m |
- operation over full temperature range (for region in which equipment used) Suggested: - digital output (real time or archival) capability |
1 minute | 1 minute |
| Cloud Amount | 1 okta (1/8th of the sky) if instrumentation is in use | - operation over full temperature range (for region in which equipment used) Suggested: - digital output (real time or archival) capability |
1 minute | 1 minute |
| Visibility | ± 50 m up to 500 m ± 10% from 500 m to 1500 m ± 20% for beyond 1500 m if measured by instrument |
- operation over full temperature range (for region in which equipment used) Suggested: - digital output (real time or archival) capability |
1 minute | 1 minute |
| Wave Height | ± 3% for periods 2 to 20 s ± 6% for periods 21 to 30 s |
- operation over range 0 to 30 m |
Combined Significant Wave Height 20 minutes Maximum Wave Value 20 minutes Wave Spectral Period 20 minutes Wave Spectra 20 minutes |
Combined Significant Wave Height 20 minutes Maximum Wave Value 20 minutes Wave Spectral Period 20 minutes Wave Spectra 20 minutes |
| Wave Direction(s) | ± 5 degrees | - recording interval between 17.5 and 35 minutes - continuous recording interval height criteria reached - digital output (real time or archival) capability |
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| Sea Surface Temperature | ± 0.5 degrees Celsius | - operation over range of -2oC to 25oC | 1 minute | 1 minute[5] |
| Water Level | 0.01 metre | - digital output (real time or archival) capability - operation over full temperature range (for region in which equipment used) |
10 minutes | 1 hour |
| Water Temperature | ± 0.5 degrees Celsius | - digital output (real time or archival)
capability - operation over full temperature range (for region in which equipment used) |
No longer than ½ hour for moored measurements, and monthly (preferably) or seasonally for CTD profiles | |
| Salinity | ± 1 part per thousand | - digital output (real time or archival) capability - operation over full salinity range (for region in which equipment used) |
No longer than ½ hour for moored measurements, and monthly (preferably) or seasonally for CTD profiles | |
| Depth | ± 0.2 metre | - digital output (real time or archival) capability - operation over full depth range (for region in which equipment used) |
No longer than ½ hour for moored measurements, and monthly (preferably) or seasonally for CTD profiles | |
| Ocean Currents: horizontal current speed and direction | ± 0.02 m/s for range 0-3 m/s ± 5o for range 0-360o |
- record at near-surface, mid-depth and near-bottom depths - apply averaging intervals of at ≥ 5 minutes |
No longer than ½ hour | |
| Heave, pitch and roll | As provided | Equipment provided by the Operator | ||
[1] Sensor model/serial number, sensor height, siting description, record specification, trip report (if required), local chart datum (if required), equipment data sheet. |
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OCEANOGRAPHIC
Mooring Considerations
Moorings or deployments should be maintained in one location for as long as possible and need not be moved with every relocation of an Installation in a particular area. Consideration should be given to mooring or deployment longevity rather than relocation, whenever possible. Both the location and design of the moorings or de ployment should be included in the Program Description described in Section 1.2.
The wave measuring instrument should be located so that the wave field being measured is not disturbed by the Installation and located sufficiently close to the Installation so that reliable communications between the wave instrument and the receiver on the Installation are maintained. The instrument should also be located so that the wave field being measured is not substantially altered from that at the site of the Installation because of sheltering, bottom effects, etc., or in general have a different exposure to prevailing conditions.
ICE MANAGEMENT
Instruments for ice detection and monitoring primarily include radar, which are generally operated from a drilling unit, ship, or aircraft. Instruments should be selected to optimize performance in a number of areas, including: range, target size detection and detection of small ice masses, detection in poor weather and sea conditions, and target tracking. In situ measurements of above-surface iceberg size are generally obtained using camera or sextant. Sonar and other underwater equipment, ROV or AUV, are generally used for draft measurement.
The Operator is encouraged to discuss existing or potential instrument and detection and measurement technologies with other operators and ice service groups to ensure that the most appropriate tools are used.
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