Metadata Report for BODC Series Reference Number 2245587

• 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 for Current Profiles from UK-OSNAP Icelandic Basin Mooring Deployed During Cruise AR30-04 at site IB5

Screening and Quality Control

During BODC quality control, data were screened using in house visualisation software and any obvious outliers and spikes were looked at in closer detail and flagged if necessary.

DBINAA01

The downward facing Teledyne RDI Workhorse 300 kHz ADCP (Acoustic Doppler Current Profiler) (s/n 13872) recorded rank 2 parameters in 28 bins. The recorded depth for each bin (DBINAA01) is constant for this instrument. No flags have been applied in this case.

For the the upwards facing Teledyne RDI Workhorse 300 kHz ADCP (s/n 13872), the nominal depth of the instrument was 8.9 metres. However, due to the file convention, the shallowest bins in the data are stored with negative 'Z' values. These values were automatically flagged 'M' during transfer to BODC's internal format (QXF), as they are outside of parameter limits, and BODC do not alter original values. Therefore, FDEPTH (the minimum depth of the series) is set to 0 metres as a surface-capped minimum consistent with the archived depth axis.

LCEWAP01, LCNSAP01, LRZAAP01 and LERRAP01

Both the upward and downward facing ADCPs occasionally recorded values of -3276.80 cm/s for current velocity parameters. Values for currents below -500 cm/s are outside of BODC parameter limits, indicating there may be a problem with the data. BODC flag 'M' was applied to each occurrence of this value. BODC flag 'M' was also applied to a small number of large spikes in current data and any further points outside of the parameter limits.

PCGDAP02

Acceptable proportion of acoustic signal returns, from beam 2, had a constant value of 0% for all 28 bins of the downward facing ADCP. This parameter was also constant at 0% for bins 1 through 19, for the upward facing ADCP. No BODC flags have been applied to these values.

Overall, approximately 20% of downward facing ADCP (s/n 13872) data, and approximately 10% of upward facing ADCP (s/n 20959) data, have been flagged 'M' by BODC.

Both depth and current data were recorded by the same instrument: Teledyne RDI Workhorse 300 kHz ADCP.

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

RD Instruments 300kHz Workhorse Sentinel Acoustic Doppler Current Profiler

Specifications

The manufacturer's specification document can be found here

Processing by BODC of Current Profiles from UK-OSNAP Icelandic Basin Moorings Deployed During Cruise AR30-04 at IB3, IB4, and IB5 Sites

The Teledyne RDI Workhorse 300 kHz ADCP (Acoustic Doppler Current Profiler) water current velocity data were supplied to BODC as ASCII files. The measurements were collected at the UK-OSNAP IB3, IB4, and IB5 mooring sites in the Icelandic Basin and span a two-year period, with deployment during cruise AR30-04 in 2018 and recovery during cruise DY120 in 2020.

The originators variables were mapped to unique BODC parameter codes during conversion to the BODC internal format (QXF). The table below shows the parameter mapping.

Following transfer the data were screened using BODC in-house visualisation software. Channels that were not transferred are available in the originator's format upon request.

Data Flagging

• Suspect data values were assigned the appropriate BODC data quality flag.
• Absent data values have been flagged null and replaced with the respective BODC parameter's missing data value.
• Values interpreted as originator null values have been retained as supplied. These values have been assigned the BODC quality control flag "M" to indicate uncertainty in their interpretation. No modification has been made to the original numeric values.

Processing by Originator of Current Profiles from UK-OSNAP Icelandic Basin Moorings Deployed During Cruise AR30-04 at IB3, IB4, and IB5 Sites

Sampling Strategy

During the RV Neil Armstrong cruise AR30-04, three pairs of downward- and upward-looking Teledyne RDI Workhorse 300 kHz Acoustic Doppler Current Profilers (ADCPs) were deployed at the UK-OSNAP mooring sites IB3, IB4, and IB5 in the Icelandic Basin.

Each mooring was equipped with paired ADCPs to obtain high-resolution vertical profiles of ocean current velocities throughout the water column. The combination of upward- and downward-looking instruments allowed for extended coverage and improved data continuity across depth ranges. The moorings were subsequently recovered during the RRS Discovery cruise DY120.

Data Acquisition and Initial Processing

The ADCPs were configured to ping 42 times per hour (approximately one ensemble every 86 seconds). The instruments were programmed with 30 depth cells, each with a vertical bin size of 4 m, providing a total profiling range of approximately 120 m per instrument.

For the planned two-year deployment, battery consumption was estimated at approximately 80%, ensuring sufficient power reserves for continuous operation throughout the mooring period.

Full details of the originators processing of the raw ADCP data files are provided in Section 26.4 of the DY120 cruise report.

The processed and quality-controlled datasets were subsequently supplied to the British Oceanographic Data Centre (BODC) for long-term archival and data banking.

Project Information

UK - Overturning in the Subpolar North Atlantic Programme (UK-OSNAP) Programme

UK-OSNAP is part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic. The aim is to quantify and understand the Subpolar Gyre's response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the Atlantic Meridional Overturning Circulation (AMOC).

UK-OSNAP is developing a new observing system to provide a continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes. Combining these sustained measurements with innovative modelling techniques will enable the project to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre.

UK-OSNAP is funded by the Natural Environment Research Council (NERC). The project is led by the National Oceanography Centre (NOC) with partners in the University of Liverpool, the University of Oxford and the Scottish Association for Marine Science (SAMS). It is a part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project involves fieldwork at sea and model studies.

The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.

NERC have added an extension to UK-OSNAP, until October 2024. This will result in the UK-OSNAP-Decade: 10 years of observing and understanding the overturning circulation in the subpolar North Atlantic (2014-2024).

Data Activity or Cruise Information

Data Activity

Ellett Array Moored Instruments IB5 2018-2020

This rig was deployed as part of the Iceland Basin Array.

The rig was held down by a 1300 kilogram anchor on the seabed at 900 metres depth. It was kept erect by 44" syntactic float at 75 metres depth and 2 glass spheres at 30 metres depth.

The instruments deployed on the rig were as follows:

There were no issues with any of the sensors reported.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Extended Ellett Line: Fixed Station IB5

Station IB5 is one of the fixed CTD stations, which together form The Extended Ellett Line. The line lies between Iceland and the Sound of Mull (Scotland) crossing the Iceland Basin and Rockall Trough via the outcrop of Rockall. As part of this initiative, CTD dips, together with associated discrete sampling of the water column, have typically been carried out annually at this station since September 1996.

From 2018 this mooring contributed to the UK-OSNAP project. It was referred to as the OSNAP Iceland Basin Array.

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: IB5_07_2018

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: Extended Ellett Line Station IB5

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.