Metadata Report for BODC Series Reference Number 1205815

• 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 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

RRS Discovery short term mooring instrument description

Sampling Strategy

Short term mooring ADCP data were collected on cruise RRS Discovery D376 using the instrumentation detailed below.

No manufacturer's calibration information is available.

The ADCP's configuration has been setup in the following ways.

No changes to the mooring instrumentation were recorded during these cruises.

Teledyne RDI's Workhorse Long Ranger ADCP

The Workhorse Long-Ranger acoustic doppler current profiler (Teledyne RD Instruments) is a long-range and long-term self contained ADCP. It has a patented broadband signal (75 kHz) and a standard depth rating of 1500m. It operates effectively between temperatures of -5°C and 45°C and has a velocity accuracy of ±1% ±5mm/s.

The instrument comprises:

• An aluminium transducer head with four beams at 20^o from the vertical in a convex configuration, temperature sensor, electronic assemblies, fluxgate compass, pitch and roll sensors
• 4 x 28 D-cell alkaline battery packs
• 40 MB PC card internal memory (upgradeable to 440 MB)
• 1500m depth rated 6061 aluminium pressure case. End cap with wet material connector and dummy plug

D376 moored instrumentation: Originator's data processing

Sampling Strategy

The RRS Discovery D376 was the first of two cruises funded by the NERC Consortium grant for the Fluxes Across the Sloping Topography of the North East Atlantic (FASTNEt) project. D376 was a 19 day cruise sailing on 11 June 2012 from Swansea dry dock to the Celtic Sea shelf edge where a total of six short term ADCPs were deployed before returning to Southampton on 2 July 2012.

Data Processing

The originator has done the following quality control on the data before submitting to BODC.

Data contaminated by the stronger surface echo has been removed from ST3 and ST4 by calculating the maximum range for acceptable current readings based on the following:

Rmax = D cos(θ)

where D = distance from ADCP to surface, θ = ADCP beam angle.

All data above this level has been removed (after additional visual inspection).

At ST5 and ST1 a cut off at 147.8 mab (metres above bottom) and 624.56 mab was applied.

No data was removed from the two ADCPs at ST2 since they stopped profiling a considerable distance from the surface.

No data has been removed from within the water column at any of the sites and quality control here has been left to the discretion of the user.

All the velocity data (est_vel, nrt_vel) has been corrected for magnetic declination. The appropriate declination was calculated using the GeoMag 7.0 software.

All files supplied to BODC have undergone trimming to remove data cycles from before the ADCP was deployed and from after it had been recovered.

The binary data from the instrument was exported into a MATLAB file using the WinADCP software (v1.14). This data was then converted into a MATLAB structure. The originator has applied a correction for magnetic declination = -4.3667° (magnetic north to the west of true north).

The binary data from the instrument was exported into a MATLAB file using the WinADCP software (v1.14). This data was then converted into a MATLAB structure. The originator has applied a correction for magnetic declination = -4.35° (magnetic north to the west of true north).

The binary data from the instrument was initially converted to ASCII using the Flowquest software. This data was then converted into a MATLAB structure. The originator has applied a correction for magnetic declination = -4.33° (magnetic north to the west of true north).

The binary data from the instrument was initially converted to ASCII using the Flowquest software. This data was then converted into a MATLAB structure. The originator has applied a correction for magnetic declination = -4.25° (magnetic north to the west of true north).

The binary data from the instrument was initially converted to ASCII using the Flowquest software. This data was then converted into a MATLAB structure. The originator has applied a correction for magnetic declination = -4.40° (magnetic north to the west of true north). The originator has stated that there may be potential contamination in the bottom 3 bins caused by the recovery line on the frame. A three beam solution is possible after identification of the contaminated beam using error velocity, echo amplitude, percentage good and correlation.

Field Calibrations

The originator has stated that no field calibrations were undertaken.

Processing by BODC of RRS Discovery short term ADCP data

Data from 6 ADCPs arrived at BODC in MATLAB files. Data from three ADCP's were from short term in-line moorings (ST1, ST2UW and ST2LW) and three ADCP's were fixed to bedframes (ST3, ST4 and ST5). The data have been converted to BODC's internal QXF format.

The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.

Due to the inherently noisy nature of ADCP data, only obvious spikes were looked at in closer detail and flagged if necessary.

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

• Irregularities such as unfeasible values
• Inconsistencies between related information, for example:
  • Times for instrument deployment and for start/end of data series
  • Length of record and the number of data cycles/cycle interval
  • Parameters expected and the parameters actually present in the data cycles
• Originator's comments on meter/mooring performance and data quality

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

• Spurious data at the start or end of the record.
• Obvious spikes occurring in periods free from meteorological disturbance.
• A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

• Maximum and minimum values of parameters (spikes excluded).
• The occurrence of meteorological events.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.

Project Information

Fluxes Across Sloping Topography of the North East Atlantic (FASTNEt)

Background

The FASTNEt consortium was funded to deliver NERC's Ocean Shelf Edge Exchange Programme. Commencing in October 2011, this four year study aims to couple established observational techniques, such as moorings and CTDs, with the very latest in autonomous sampling initiatives - including use of Autosub Long Range and gliders. With the aid of novel model techniques, these observations will be utilised to construct a new paradigm of Ocean/Shelf exchange.

Shelf edge regions mark the gateway between the world's deep oceans and shallower coastal seas, linking terrestrial, atmospheric and oceanic carbon pools and influencing biogeochemical fluxes. Shelf edge processes can influence near-shore productivity (and fisheries) and ultimately affect global climate.

FASTNEt brings together researchers from multiple UK organisations. Further collaboration has been established with five Project Partners: the UK Met Office, Marine Scotland Science, Agri-Food and Biosciences Institute, Marine Institute Ireland and Scripps Institution of Oceanography.

Scientific Objectives

• To determine the seasonality of physical gradients and exchange across the shelf edge by deploying new observational technologies (gliders, Autosub Long Range) and established techniques (long term moorings, drifters)
• To quantify key exchange mechanisms and to collect new data targeted at testing and improving high resolution models of the shelf edge, by carrying out detailed process studies in contrasting regions of the shelf edge of the NE Atlantic margin
• To develop a new parameterisation of shelf edge exchange processes suitable for regional-scale models, using improved resolution numerical, and new empirical models constrained by the observations
• To test the new parameterisations in a regional model in the context of making an assessment of inter-annual variability of ocean-shelf exchange.

Fieldwork

Three survey sites on the UK shelf edge have been selected for FASTNEt. These are a) the Celtic Sea shelf edge, b) Malin shelf and c) North Scotland shelf. Fieldwork is centred around two research cruises. The first, to the Celtic Sea, on RRS Discovery in June 2012. The second cruise visits the Malin shelf on RRS James Cook, during summer 2013. In addition to these dedicated cruises, opportunist cruise activity to the North Scotland shelf has been agreed with project partner Marine Scotland Science. Autonomous technologies will complement observations made during the cruises and provide knowledge of seasonal and inter-annual variability in exchange processes.

Instrumentation

Types of instruments/measurements:

• Gliders
• Autosub Long Range
• Drifter buoys
• Scanfish
• Microstructure profilers
• Moored CTD/CT loggers and ADCPs
• Shipboard measurements: CTD, underway, nutrients (and other discrete sampling), LADCP, ADCP.

Contacts

Data Activity or Cruise Information

Data Activity

FASTNEt single point mooring ST1

The short term mooring ST1 was deployed and recovered during cruise RRS Discovery D376 which took place between 11 June 2012 to 2 July 2012 as part of the Fluxes Across the Sloping Topography of the North East Atlantic (FASTNEt) project.

The mooring was kept upright by a large sub-surface float (at 31 m depth), supplemented by groups of deeper smaller buoys. The mooring incorporated a pellet at 15 m depth.

Instruments deployed on the mooring

Instrument codes

AC - 75 kHz RDI ADCP

CT - Star-Oddi DST centi-T Temperature Recorder

MC - SBE 37 MicroCAT

ML - Vemco Minilogger

Bad data were produced by Vemco Miniloggers 1087, 1106, 3894, 5593 and 6177 and so were not taken through by the Originator.

Related Data Activity activities are detailed in Appendix 1

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:

Appendix 1: ST1

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.