Metadata Report for BODC Series Reference Number 1223428

• 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

Sea-Bird SBE 37-SM MicroCAT

The SBE 37-SM MicroCAT is a high accuracy conductivity and temperature recorder (pressure optional). Designed for moorings and other long-duration, fixed-site deployments, MicroCATs have non-corroding titanium housings rated for operation to 7000 metres or pressure sensor full scale-range. Communication with the MicroCAT is over an internal, 3-wire, RS-232C link. The MicroCAT's aged and pressure-protected thermistor has a long history of exceptional accuracy and stability (typical drift is less than 0.002° per year). Electrical isolation of the conductivity electronics eliminates any possibility of ground-loop noise.

Specifications

Further information can be found via the following link: SBE 37-SM MicroCAT Datasheet

Data Processing Notes

Data submitted to BODC were transferred using standardised procedures and originator's parameters were matched to the BODC parameter vocabulary. Unit conversions were applied when originator's units did not match the ones specified on the dictionary.

Once data were transferred, several checks were performed on the file's header and data cycles. These include:

• Irregularities such as unfeasible values
• Inconsistencies between related information, namely depths of meter and sea bed (when available), times for mooring deployment and for start/end of data series, length of record or number of data cycles, cycle interval, clock error, parameters stated as measured and the parameters actually present in the data cycles
• Originator's comments on instruments/mooring performance
• Data quality

Data were inspected visually for anomalous values, spikes, jumps, effects of mooring "knock-down" and quality flags applied where appropriate. The term 'knock-down' refers to the situation when the 'drag' exerted on a mooring at high current speeds may cause instruments to tilt beyond the angle at which they are intended to operate. At this point the efficiency of the current sensors to accurately record the flow is reduced.

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

• Maximum and minimum values of parameters (spikes excluded)
• The orientation and symmetry of the current vector scatter plot
• The direction of rotation of the current vectors
• The approximate amplitude and periodicity of the tidal currents
• The occurrence of meteorological events
• The presence of water masses captured by similar instruments

Originator's Data processing

Sampling strategy

Sampling was carried out as part of the BAS LTMS (British Antarctic Survey Long Term Monitoring and Survey) until 2016. From 2016 onwards the moorings are split between 'The Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)' project and 'Dynamics of the Orkney Passage Outflow (DynOPO)' project.

The projects involve the deployment of moorings CI1, CI2, OP1, OP2, OP3, OP4, OP5, OP6 and OP7 in the Southern Ocean, situated north of Coronation Island and the Orkney Passage in the Weddell and Scotia Sea.

Moorings CI1 and CI2 were deployed from 2005 to 2007 and moorings OP1, OP2, OP3, OP4, OP5 and OP6 have been continuously maintained since 2007 with the addition of OP7 in 2015.

SBE 37 and SBE39 instruments were deployed on the moorings. Data have been collected at variable intervals: 5 minutes interval on the Coronation Island moorings, 7.5 minute interval on the instruments deployed on OP2 and OP3 in 2007 and 15 minute intervals since then. Gaps in the series may be caused by either instruments not being recovered, or data not being collected due to instrument malfunction.

Data processing

Little information is known with regards to the exact details of the calibrations carried out on the mooring data. Data processing, visualisation and calibration were carried out through the use of scripts for Matlab version R2014b produced and ran by the originator.

An offset has been applied some of the channels. The values for each deployment/instrument/channel combination are shown in the table below:

Several instruments deployed in the 2013/15 period show evidence of knock-down but the data colleaction seems to be unnafected. According to the originator some of the moorings were deployed with insufficient buyoancy which caused the knockdowns. These instances are especially visible on moorings OP1 and OP2, Series Reference number 1840205, 1840229, 1840254, 1840266 and 1840278

Several instruments deployed in the 2015/17 period did not have a pressure sensor and used inferred pressure calculated from the closest neigbhouring pressure sensor. This includes five SBE39 instruments (s/n 4413, 4716, 4713, 4418 and 4409) and one SBE37 instrument (s/n 8267).

Several instruments deployed in the 2017/19 period did not have a pressure sensor, therefore no pressure channel was transferred with the data and only a nominal depth is used in the metadata. This includes all SBE39 instruments (s/n 4413, 4409, 0083, 4713, 4418 and 4716) and one SBE37 instrument (s/n 8267).

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

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

Orkney Passage mooring 2 (OP2)

The mooring was deployed at the following positions:

The mooring was deployed on the Orkney Passage on cruise JR20110319 (JR252, JR254C) on 27 March 2011 and recovery was done on cruise JR20130317 (JR272B, JR273A, JR281, UKD-4) on 30 April 2013.

The table below lists the instruments deployed on this mooring:

Data issues upon recovery

The recovery for this mooring presented some difficulties due to the presence of ice. Several floatation buoys were dragged under floes. No data were recovered for SBE37 SN 7381 due to the start command not being sent to the instrument before deployment.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Orkney Passage OP2 site

Site OP2 is part of the Orkney Passage mooring array which is an activity covered by the Long Term Monitoring and Survey British Antarctic Survey's (BAS) programme. The data collection is the result of an ongoing collaboration between BAS and the Lamont-Doherty Earth Observatory (LDEO).

This site has been occupied since 2007 but throughout the years it has been moved. The recovery/deployment history, including position details, is presented below:

Detailed information for each deployment can be accessed from the OP2 Data Activity document.

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: OP2

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: Orkney Passage OP2

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.