Metadata Report for BODC Series Reference Number 894985

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Quality Report

The relative eastward and northward current velocity channels (LREWAS01 and LRNSAS01) show a large amount of variability when the ship is travelling at relatively high speeds. The absolute eastward and northward current velocities (LCEWAS01 and LCNSAS01) are derived using the relative current velocities and therefore inherit this variability from the parent data.

These data channels have not been flagged but the end user should be made aware that such variability exists.

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.

¹ Ranges at 1 to 5 knots ship speed are typical and vary with situation.
² Single-ping standard deviation.
³ User's choice of depth cell size is not limited to the typical values specified.

Profile Parameters

• Velocity long-term accuracy (typical): ±1.0%, ±0.5cm/s
• Velocity range: -5 to 9m/s
• # of depth cells: 1 - 128
• Max ping rate: 0.7

Bottom Track

Maximum altitude (precision <2cm/s): 950m

Echo Intensity Profile

Dynamic range: 80dB
Precision: ±1.5dB

Transducer and Hardware

Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W

Standard Sensors

Temperature (mounted on transducer)

• Range: -5° to 45°C
• Precision: ±0.1°C
• Resolution: 0.03°

Environmental

Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*

*later instruments have greater range.

Web Page

Further details can be found on the manufacturer's website or in the specification sheet

D340B 75kHz VMADCP processing

Configuration

The 75 kHz ADCP on board the RRS Discovery is an Ocean Surveyor broad band phased array VMADCP mounted in the hull in a second water chest 4.15 m forward and 2.5 m to the starboard of the 150kHz well which is situated 1.75 m to the port of the keel and 33 m aft of the bow at the water line. The VMADCP was configured to sample over 120 second intervals with 100 bins of 8 m depth and a blank beyond transmit of distance of 8 m. The VMADCP was configured to run in 'Narrowband' range over resolution mode with bottom tracking used over the Icelandic and UK continental shelves.

Data Originator's Processing

• Data acquisition

  Data were processed using the following scripts:

  • s75exec0: data read into Pstar format from the raw RDI binary format file; Water track velocities written into 'sur' files and bottom track into 'sbt' files whilst in bottom track mode; Velocities scaled to cm/s and amplitudes by 0.45 into db; Time variable corrected to GPS time by combining the PC clock time and the PC-GPS; perform nominal edits and adjust bin depths to correct levels.

  • s75exec1: data edited according to status flags (velocity data replaced with absent data if variable '2+bmbad' was greater than 25%); Time of ensemble moved to the end of ensemble period.

  • s75exec2: merged data with Ashtech-a ghdg; ADCP velocities converted to speed and direction allowing heading correction to be applied; ADCP velocities returned to east and north components.

  • s75exec3: applied misalignment angle ø and scaling factor A.

  • s75exec4: merged ADCP data with the bestnav data. Ship's velocity calculated from spot positions and applied to ADCP velocity producing absolute velocity of the water; Time base of ADCP profiles shifted to the centre of the 2 minute ensemble by subtracting 60 seconds.

• Calibration

  Calibration was achieved by using bottom tracking data made available after departure from Reykjavík across the Icelandic continental shelf. Using long, straight and steady speed sections of standard 2 minute ensemble profiles over reasonably constant depths the following calibrations for misalignment angle, ø, and necessary amplification (tilt), A, were derived;

  	ø	A
  Mean	0.03462772	1.001979978
  SD	0.14342535	0.002759036

BODC post-processing and screening

• Reformatting

  The data were converted from P* format into BODC internal format (QXF) to allow use of in-house visualisation tools.

• Screening

  Reformatted data were visually checked using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

• Banking

  Once quality control screening was complete, the data were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.

Project Information

Oceans 2025 Theme 3: Shelf and Coastal Processes

Over the next 20 years, UK local marine environments are predicted to experience ever-increasing rates of change - including increased temperature and seawater acidity, changing freshwater run-off, changes in sea level, and a likely increase in flooding events - causing great concern for those charged with their management and protection. The future quality, health and sustainability of UK marine waters require improved appreciation of the complex interactions that occur not only within the coastal and shelf environment, but also between the environment and human actions. This knowledge must primarily be provided by whole-system operational numerical models, able to provide reliable predictions of short and long-term system responses to change.

However, such tools are only viable if scientists understand the underlying processes they are attempting to model and can interpret the resulting data. Many fundamental processes in shelf edge, shelf, coastal and estuarine systems, particularly across key interfaces in the environment, are not fully understood.

Theme 3 addresses the following broad questions:

• How do biological, physical and chemical processes interact within shelf, coastal and estuarine systems, particularly at key environmental interfaces (e.g. coastline, sediment-water interface, thermocline, fronts and the shelf edge)?
• What are the consequences of these interactions on the functioning of the whole coastal system, including its sensitivity and/or resilience to change?
• Ultimately, what changes should be expected to be seen in the UK coastal environment over the next 50 years and beyond and how might these changes be transmitted into the open ocean?

Within Oceans 2025, Theme 3 will develop the necessary understanding of interacting processes to enable the consequences of environmental and anthropogenic change on UK shelf seas, coasts and estuaries to be predicted. Theme 3 will also provide knowledge that can improve the forecasting capability of models being used for the operational management of human activities in the coastal marine environment. Theme 3 is therefore directly relevant to all three of NERC's current strategic priorities; Earth's Life-Support Systems, Climate Change, and Sustainable Economies

The official Oceans 2025 documentation for this Theme is available from the following link: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: