Metadata Report for BODC Series Reference Number 1904696

• 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

Teledyne RDI Workhorse Sentinel 600 kHz Acoustic Doppler Current Profiler (ADCP)

The Workhorse Sentinel is a self-contained ADCP that can be used either on a mooring or mounted in the hull of a moving vessel. Its 4-beam design provides a redundant data source (in case of a blocked or damaged beam), an independent data quality measure (error velocity) and reduces the variance in data, thereby improving data reliability, quality and accuracy.

Real-time data can be transmitted to shore via a cable link or acoustic modem or they can be stored internally. Sensors for bottom tracking, pressure and directional wave measurements can be added to the instrument and a special casing is available for deeper applications.

Specifications

Further details can be found in the manufacturer's specification sheet.

Stratified Shelf Seas ADCP mooring August 2012: BODC Processing

Data from two moored ADCPs arrived at BODC in tab delimited text files. Mooring A was active between 10/08/2012-22/08/2012 and mooring B was active between 22/08/2012-02/11/2012. Data from these moorings were part of the Stratified Shelf Seas project. These files were converted into a MATLAB file for transfer into BODC's database using established BODC procedures. The variables in the original files were mapped to appropriate BODC parameters as seen below:

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

*The beam percentages were supplied by the originator but they are not included in the final BODC files. They are available on request in the original format.

Stratified Shelf Seas ADCP mooring August 2012: Originator's processing

Sampling Strategy

Two moored ADCPs were deployed using the Plymouth University vessel, RV Falcon Spirit. Mooring A was active between 10/08/2012-22/08/2012 and mooring B was active between 22/08/2012-02/11/2012. Data were collected for NERC grant NE/I001832/1 - Assessing the sensitivity of marginally stratified shelf seas within a changing climate.

Data Processing

No post-processing was applied to the file. It was submitted to BODC as raw ASCII format from the instrument.

No quality control flags have been applied to the files.

Field Calibrations

No field calibrations were undertaken.

Project Information

NERC Discovery Science - Assessing the sensitivity of marginally stratified shelf seas within a changing climate

Background

Continental shelf seas are extremely important because of the high levels of primary productivity that they sustain and their ability to absorb and sequester atmospheric gases including climatically important greenhouse gases. The key physical aspect of shelf seas that enables them to do so is the vertical density stratification, established throughout spring and summer when the stabilizing influence of solar radiation or fresh water overcomes the destabilizing influence of turbulent mixing.

In several places around the UK, such as the Irish Sea, well-established fronts form between stratified and vertically well-mixed water due to the well-understood dominant effect of friction generated at the sea bed by strong tidal currents whose influence extends throughout the water column. Throughout the majority of UK coastal waters tidal mixing is less dominant, however, and the competition between turbulent mixing and restratification is more delicately poised. Stratification and the resulting ephemeral fronts are transient in space and intermittent in time.

We are currently hindered in our ability to predict how these marginally stratified shelf seas will respond to change, however, because we do not fully understand the details of the turbulent mixing and restratification processes that govern the dynamic balance. Amongst these, surface and internal waves both exert an important but unclear influence over mixing, whilst lateral density gradients near the surface and seabed have recently been shown to modulate mixing and restratification. This lack of understanding is apparent from our inability to accurately simulate shelf sea dynamics in numerical models that are used to predict future changes.

The importance of this project stems from the realization that future changes to the Earth system are now inevitable due to climate change and will be particularly felt within marginally stratified shelf seas for which the balance between turbulent mixing and restratification is so sensitive to external perturbations. Furthermore, in order to produce 40% of the UK's electricity from renewable sources as required by EU law, a huge expansion into the marine environment to exploit its energy resources is expected.

This project was funded by the NERC Discovery Science grant NE/I001832/1 - Assessing the sensitivity of marginally stratified shelf seas within a changing climate.

Scientific Objectives

• To identify the processes involved in the existence and intensity of the front displays that are not governed by tidal periodicities.
• To test whether the processes that were identified as important to changes in shelf sea stratification through in-situ measurements are indeed responsible for the observed changes.
• To incorporate new knowledge into state-of-the-art numerical models that can up-scale the processes observed within this project to the shelf sea environment.

Fieldwork

To better understand which processes are most important within marginally stratified shelf seas, the plan is to conduct a rigorous field study and monitoring campaign in the southern Celtic Sea.

• Conduct a series of in-situ measurements of turbulence throughout the water column and by mapping the frontal structure.
• Monitor the long term trends in the forcing mechanisms and frontal integrity using seabed sensors and land-based radar that measures surface waves and currents over a broad spatial area.

The data were acquired from the RV Falcon Spirit, the Plymouth University vessel. The small 14m catamaran was used on a daily basis from 10 August 2012 to 22 August 2012.

Instrumentation

Types of instruments/measurements:

• Turbulence microstructure
• Moored temperature loggers
• VMADCP
• Moored ADCPs
• Minibat towed undulator transects

Contacts

Data Activity or Cruise Information

Data Activity

Stratified Shelf Seas ADCP mooring August 2012 for NERC grant NE/I001832/1

The ADCP was in an MSI bed frame, and the mooring was kept upright by a large sub-surface float.

Instrument deployed on the mooring

614 kHz Broadband Upward facing ADCP

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: mADCP_201208_B

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.