Metadata Report for BODC Series Reference Number 1894621

• 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

Orkney Passage Moorings 2015 - 2017 Data Quality Report

For several series during the 2015 - 2017 deployment the mooring fluctuacted in the water column by 40 - 200 metres. This includes SBE37, SBE39 and Aquadopp instruments.

The affected SBE39 series include: series reference number 1891555, 1891567, 1891579 and 1891611.

The affected SBE37 series include: 1880871, 1880883, 1880895, 1880902, 1880914, 1880926, 1880938, 1880951, 1880963, 1880975, 1880987, 1880999, 1881002, 1881026, 1881038, 1881051, 1881063, 1881075, 1881087, 1881099, 1881106, 1881118, 1881131, 1881179, 1881211, 1881223, 1881235, 1881247, 1881259, 1881260, 1881296, 1881303, 1881315, 1881327, 1881339, 1881340, 1881352, 1881364, 1881376 and 1881388.

The affected Aquadopp series include: 40600, 40800, 40900, 41000, 41100, 41200, 41300, 41400, 41500, 41600, 41700, 41800, 41900, 42300, 42400, 42500, 42600, 42700, 42800, 42900, 43000, 43100, 43600, 43700, 43800, 43900, 44000, 44100, 44600, 44700, 44800, 44900, 45000, 45100, 45200, 45300 and 45400.

These fluctuations do not appear to have affected the temperature data and therefore no flags have been added.

Orkney Passage Moorings: 2015 - 2017 Quality Control Flags

Flags were added to each parameter by the data originator. These flags correspond to WOCE quality control flags.

The flags were converted to BODC flags during BODC processing procedures and the conversion is displayed in the table below:

Originator's improbable data flags (L flags) were applied to the following SBE37 series reference numbers: 1880975, 1881106, 1881167, 1881211, 1881223, 1881235, 1881247, 1881259, 1881260, 1881303, 1881339 and 1881376.

Originator's improbable data flags (L flags) were applied to the following RCM11 series reference numbers: 1893710 and 1893734.

Originator's improbable data flags (L flags) were applied to the following Aquadopp series reference numbers: 1894344, 1894356, 1894368, 1894381, 1894393, 1894400, 1894412, 1894424, 1894436, 1894448, 1894461, 1894473, 1894485, 1894497, 1894516, 1894528, 1894541, 1894553, 1894565, 1894577, 1894589, 1894590, 1894608, 1894621, 1894633, 1894645, 1894682, 1894694, 1894701, 1894786, 1894798, 1894805, 1894817, 1894829, 1894830, 1894842, 1894854, 1894866 and 1894878.

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

Nortek Aquadopp Open Water Current Meter

This instrument provides 3D acoustic doppler current measurements along with standard measurements of temperature, pressure, tilt and direction. It can be used in real time measurement situations or can log to an internal recorder powered by internal batteries. It can also be configured to measure surface wave height, period and direction concurrently. It has the unique feature of being run in 'diagnostic' mode when set to collect data at 1 Hz frequency in user specified intervals. This allows studies of mooring motion and the performance of other current meters to be conducted. It can be set in various configurations with titanium housings for deployment at greater depths.

Standard Measured Parameters

• 3D current velocity (East/North/Up, X/Y/Z or Beam 1/2/3)

• Acoustic signal strength (Beam 1/2/3)

• Compass

• Tilt

• Temperature

• Pressure

• Battery voltage

• Status code

• Error code

Surface wave monitoring

The standard Aquadopp is suitable for measuring surface wave height, period, and direction, which are calculated using the PUV method whereby spectra are estimated based on a combination of the pressure signal recorded by the instrument (P) and two horizontal components of the wave orbital velocity (U and V). More specifically, the pressure signal is used to provide an estimate of the wave frequency spectrum. The energy in this spectrum is then used to estimate wave height and period. The measurements of the wave orbital velocities are used to provide an estimate of the wave direction. Since these estimates are based on the distribution of wave energy and are not direct measurements of the free surface, they should be considered inferred estimates.

Both the dynamic pressure and the orbital velocities are driven by surface waves. The signals that are associated with these properties are complicated by the fact that they attenuate (that is the signals are weaker) with depth. The exact behaviour of the attenuation is determined by the water depth and the wavelength being observed. The greater the water depth the greater the attenuation; likewise, the shorter the wavelength (or higher the frequency of the wave) the greater the attenuation for a given water depth. This means that the estimation of wave parameters is limited by both water depth and wave frequency.

Specifications

Further details can be found in the manufacturer's specification sheets for the Aquadopp, Aquadopp 3000 and Aquadopp 6000.

BODC Processing

Data processing

The data arrived at BODC as individual .mat files containing data collected on moorings OP1, OP2, OP3, OP4, OP5, OP6, OP7, CI1 and CI2. They were submitted as part of an accession which includes data from several mooring instruments e.g. ADCP, Aquadopp, RCM8, RCM11, RBR, SBE37 and SBE39.

Reformatting

The parameters from the originator's files were reformatted to internal format using BODC standard procedures.

The following parameters from the Aquadopp data were not reformatted as they are considered metadata or are not environmental variables: date, depth (m), botdepth (m), lat/lon, mooringname, nomdepth (m), serial_no, type, temp_offset_applied and press_offset_applied.

The table below includes the final variables and how they were mapped to the appropriate BODC parameter codes:

Battery voltage and amplitude channels were reformatted to help with the screening process and are not included in the final file but are avaiable upon request.

None of the parameters required a unit conversion and no derived parameters were created during reformatting.

Screening

The reformatted data were visualised using in house software and spikes or improbable values were flagged accordingly.

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.

Aquadopp Deep Water current meters data have been collected at 15 minute intervals since 2011. Gaps in the series may be related to 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. Originator's data processing, visualisation and calibration were done through the use of Matlab scripts written for Matlab R2014b version.

The originator did not apply corrections to current velocity, direction or components for magnetic variation for the data from 2011 to 2013 as the variation in this region is less than one degree.

According to the originator, it has been found that in some conditions Aquadopp current meters overread current speeds compared with a mechanical vector measuring current meter and there is considerable uncertainty associated with the exact corrections that should be applied. Because of the continuing uncertainties of how best to correct for the differing characteristics of these instruments, no correction has been applied to these data.

Offsets applied to the data were:

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 JR20150309 (JR272D, JR310) on 04 April 2015 and recovery was done on cruise JR16005 on 14 April 2017.

The table below lists the instruments deployed on this mooring:

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.