Metadata Report for BODC Series Reference Number 770668

• 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

During screening it was identified that all the series included short periods relating to the deployment and recovery of the instrument. All instances have been flagged M for all channels.

Data Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

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

BODC Processing

The data arrived at BODC in .mat files representing acoustic doppler current profiler (ADCP) data from a mooring positioned in Marguerite Bay, Antarctica which was deployed in conjuction with the Rothera Oceanographic and Biological Time Series (RaTS). These were reformatted to the internal QXF format using BODC established procedures. The following table shows how the variables within the matlab files were mapped to the appropriate BODC parameter codes:

The originator's file also included several other parameters that weren't transferred but are available upon request: bt_range, bt_vel, corr, status, vert-vel (m s^-1), temperature (°C), salinity, pressure, pitch_std (°C), roll_std (°C), pressure_std, heading_std (°C).

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.

Originator's Processing

vertical structure of the water column data were obtained from two moorings deployed in Marguerite Bay, one on the RaTS site and the other in the subsidiary branch of Marguerite Trough. The Acoustic Doppler Current Profiler (ADCP) data were recorded at 15 minute interval all throughout the deployment period. The instruments were deployed in current profiling mode, and were upward looking. The bin closest to the ADCP was set at 12.65 m deep to prevent contamination of acoustic returns by the outgoing signal whilst the remaining bins are 4 m deep

The originator applied data selection procedures using the instrument's 'percent good' (PG) parameter, which logs the percentage of returns from each outgoing acoustic pulse that passed a variety of criteria. The PG values are affected by factors such as low correlation, large error valocity and fish detection. Any returns with PG < 75% were flagged and the corresponding velocity and acoustic backscatter data were rejected from the final file. The resulting gaps in the time series were re-built using linear interpolation.

ADCP data close to the surface were consistently poor due to the strong surface echo overwhelming the side lobe suppression of the transducer. Examination of these data revealed that the uppermost ~15m (4 bins) of all series were contaminated and therefore were discarded from the final file.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

RaTS Mooring Deployment 3

The third deployment of the mooring at the RaTS site occurred on 17th December 2006 and was later recovered on 19th April 2007. Both deployment and recovery were carried out onboard the RRS James Clark Ross.

The exact position of the mooring is as follows:

Details of the instrumentation associated with the first deployment of the mooring at the RaTS site:

Figure of mooring and table of instruments with corresponding depths (Wallace, 2007)

Reference

Wallace, M.I., 2007. Ocean circulation, properties and variability in Marguerite Bay, west Antarctic Peninsula. PhD Thesis. The Open University, Milton Keynes, UK.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Rothera Oceanographic and Biological Time Series (RaTS) Fixed Station

The RaTS fixed station is made up of 3 CTD sampling sites and 2 mooring sites. The main CTD site is located in Marguerite Bay, ~4 km from shore and over a water depth of ~520 m. Marguerite Bay is enclosed by Adelaide Island to the north, Alexander Island to the south and the Antarctic Peninsula to the east (Figure 1 and 2). Waters are strongly influenced by the Antarctic Circumpolar Current. Surface waters during summer become warm through insolation and freshened by ice melt. In winter surface waters are generally colder and more saline and characterised by a thick mixed layer which persists into the summer months and is marked by a subsurface temperature minimum (for fuller details please see Meredith et al., 2004 and references therein). When optimal conditions aren't available the secondary CTD site is occupied. In times when fast ice prevented sampling at both the primary and secondary site, a third site is utilised close to the Rothera Research Station. However, only a water sample is collected during this time as the water is too shallow to allow for a cast to be conducted. The following provides details of the CTD sites sampled:

To compliment the CTD data collected at the RaTS station, fixed moorings were deployed between 2005 - 2007. The moorings consisted of a suite of sensors including ADCPs, CTDs and sediment traps.

Figures Location of Maguerite Bay, to the west of the Antarctic Peninsula (Meredith et al., 2004) and more specifically the location of the RaTS station (Wallace, 2007)

Reference

Meredith, M.P., I.A. Renfew, A. Clark, J.C. King, M.A. Brandon (2004) Impact of the 1997/98 ENSO on upper ocean characteristics in Marguerite Bay, western Antarctic Peninsula. Journal of Geophysical Research Letters, Vol. 109, C09013, doi:10.1029/2003JC001784

Wallace, M.I., 2007. Ocean circulation, properties and variability in Marguerite Bay, west Antarctic Peninsula. PhD Thesis. The Open University, Milton Keynes, UK.

Related Fixed Station activities are detailed in Appendix 2

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: RaTS_dep3

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.

Appendix 2: RaTS, Rothera

Related series for this Fixed Station 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.