Metadata Report for BODC Series Reference Number 1618222


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Aanderaa RCM 11 Recording Current Meter  current meters
Instrument Mounting subsurface mooring
Originating Country United Kingdom
Originator Mr Povl Abrahamsen
Originating Organization British Antarctic Survey
Processing Status banked
Project(s) BAS Long Term Monitoring and Survey
 

Data Identifiers

Originator's Identifier OP4_1113_4_RCM11_532_2194M
BODC Series Reference 1618222
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2011-03-27 04:00
End Time (yyyy-mm-dd hh:mm) 2012-07-25 21:03
Nominal Cycle Interval 3600.0 seconds
 

Spatial Co-ordinates

Latitude 60.58960 S ( 60° 35.4' S )
Longitude 41.82962 W ( 41° 49.8' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 2194.0 m
Maximum Sensor Depth 2194.0 m
Minimum Sensor Height 760.0 m
Maximum Sensor Height 760.0 m
Sea Floor Depth 2954.0 m
Sensor Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ACYCAA01 1 Dimensionless Record_No Sequence number
CNDCZZ01 1 Siemens per metre Cond Electrical conductivity of the water body
LCDAZZ01 1 Degrees True UnspCurrDir Current direction in the water body
LCEWZZ01 1 Centimetres per second CurrVelE Eastward current velocity in the water body
LCNSZZ01 1 Centimetres per second CurrVelN Northward current velocity in the water body
LCSAZZ01 1 Centimetres per second UnspCurrSpd Current speed (Eulerian) in the water body
TEMPPR01 1 Degrees Celsius Temp Temperature of the water body
ZNTHSS01 1 Degrees ISTilt Orientation (tilt) of measurement platform by inclinometer
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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

Aanderaa Recording Current Meter Model 9/11

The RCM 9/11 is a family of single-point Doppler recording current meters with different casing options to allow working at depths of up to 300 (RCM 9 LW), 2000 (RCM 9 IW) or 6000 (RCM 11) metres. The recording unit is 51.3 cm or 59.5 cm high (RCM 9 and RCM 11, respectively) with a diameter of 12.8 cm.

The RCM is most commonly deployed in an in-line mooring configuration. As it operates under a tilt up to 35° from vertical, it has a variety of in-line mooring applications by use of surface buoy or sub surface buoy. The instrument is installed in a mooring frame that allows easy installation and removal of the instrument without disassembly of the mooring line. The instrument can also be used for direct reading of the various parameters. This is conveniently done due to its compact design, low drag force and easy handling. Data can be stored internally and read after retrieval or be read in real time on deck by use of the profiling cable.

Meter comprises:

A built-in quartz clock allows the time of the first measurement to be recorded in the DSU. The measuring system is made up of a self-balancing bridge with sequential measurement of 10 channels and solid state memory. Channel 1 is a fixed reference reading for control purposes and data identification. Channels 2 and 3 represent measurement of current speed and direction. The direction is found by the use of measurements along two orthogonal axis and linking them to true north by use of an internal compass reading. The instrument can operate continuously or in eight intervals from 1 to 120 minutes. At 60-minute recording interval the operating time is more than two years. The current speed and direction are averaged over the measuring interval. Channels 4, 5 and 6 represent temperature, conductivity and pressure respectively.

Further information can be found in the manufacturer's instrument specification .

BODC Data Processing

Data Processing

The data arrived at BODC as individual .mat files containing data collected on moorings OP1, OP2, OP3, OP4, OP5, OP6, CI1 and CI2. They were submitted as part of an accession including 5 different instruments - Aquadopp, RCM8, RCM11, SBE37 and SBE39.

Reformatting

Parameters in the originator's files were reformatted into an internal file format using BODC standard procedures.

Some variables included in the RCM11 files have not been reformatted into the internal format files, as they will be stored as metadata. These include - botdepth (meters), date, lat (degrees north), lon (degrees east), mooringname, nomdepth (meters), serial_no and type.

The following table lists all the parameters included in the internal format files, showing how the originator's variables as named in the matlab files were mapped to appropriate BODC parameter codes.

Originator's Variable Originator's Units Description BODC Parameter Code BODC Units Comments
speed cm s -1 Current speed (Eulerian) in the water body LCSAZZ01 cm s -1

 

dir degrees magnetic Current direction in the water body LCDAZZ01 degrees true

 

u cm s -1 Eastward current velocity in the water body LCEWZZ01 cm s -1

 

v cm s -1 Northward current velocity in the water body LCNSZZ01 cm s -1

 

tilt degrees Orientation (tilt) of measurement platform by inclinometer ZNTHSS01 degrees

 

temp deg. C Temperature of the water body TEMPPR01 degrees C

 

cond mS cm -1 Electrical conductivity of the water body CNDCZZ01 S m -1 1:0.1 conversion from mS cm -1 to S m -1
salt - Practical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm PSALPR01 - Only present in certain files. See note below

No derived parameters were calculated by BODC. Please note that the Salt parameter was only present in the files with series reference number 1618129, 1618130, 1618142, 1618154, 1618166.

Screening

Quality control flags were automatically added to data outside the expected parameter specific range during the reformatting process. All parameters were then visualised and screened using in house software, and any improbable or missing data point was assigned a quality control flag. The signal return amplitude 'sigstr' was reformatted for screening purposes only; as it is not an environmental variable, this parameter is not included in the final reformatted files, however it can be retrieved upon request.

Reference

Fofonoff and Millard (1983). Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No 44, 53pp.

Originator's Data Processing

Sampling Strategy

Sampling was carried out as part of the BAS LTMS (British Antarctic Survey Long Term Monitoring and Survey). The project involved the deployment of moorings CI1, CI2, OP1, OP2, OP3, OP4, OP5 and OP6 in the Southern Ocean, situated north of Coronation Island and the Orkney Passage in the Weddell and Scotia Sea.

Moorings OP2, OP4, CI1 and CI2 were first deployed in 2005, fitted with RCM11 instruments, and data have been collected at 60-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.

The originator reported that current direction and velocity components were not corrected for magnetic variation, as at the moorings' sites this is lower than the measurements' accuracy. The Originator also reported that under some conditions the RCM11s under-read current speeds compared with a mechanical Vector Measuring Current Meter (VMCM), as indicated by results from Watts et al. (2013, J Atmos. Oceanic Technol.). Due to continuing uncertainties regarding which correction would best resolve the different characteristics of these two instruments, the RCM11 measurements were left unmodified by the Originator.

Offsets were applied to RCM11 temperature data in two datasets:

Mooring Time period (UT) Depth Serial Number Offset Applied
OP2 2007-02-25 to 2009-02-28 2385 m 592 0.0500 deg. C
OP4 2011-03-27 to 2012-07-25 2194 m 532 0.0170 deg. C

References

Watts D.R. et al., 2013. Four current meter models compared in strong currents in the Drake Passage. Journal of Atmospheric and Oceanic Technology: 30, 2465-2477. DOI: 10.1175/JTECH-D-13-00032.1


Project Information

BAS Long Term Monitoring and Survey

Introduction

The Long Term Monitoring and Survey project (LTMS) has been running since the British Antarctic Survey (BAS) was created. This project is one of the BAS core projects, with several groups of scientists collecting various types of data e.g biological, geological, atmospheric, among others.

Data collection is achievable through a wide scope of instruments and platforms, e.g. the Antarctic research stations, autonomous instrument platforms deployed on or from BAS research ships, BAS aircrafts, satellite remote sensing and others.

Scientific Objectives

This project was implemented in order to measure change and variability in the Earth system. Its long term duration allows for the monitoring of processes that could be missed in shorter term studies and experiments. The data collected is also used to check and improve the reliability of models used to stimulate and predict the behavior of the Earth system.

The main objectives are:

Data Availability

The data sets obtained through this project are available to the academic community.


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2011-03-27
End Date (yyyy-mm-dd) 2013-04-03
Organization Undertaking ActivityBritish Antarctic Survey
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierOP4
Platform Categorysubsurface mooring

Orkney Passage mooring 4 (OP4)

The mooring was deployed at the following positions:

Organisation Undertaking Activity British Antarctic Survey, Cambridge
Country of Organisation United Kingdom
Originator's Data Activity Identifier OP4
Platform Category Subsurface mooring
Latitude (+ve N) -60.5896
Longitude (+ve E) -41.8296
Water Depth (m) 2962

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 03 April 2013.

The table below lists the instruments deployed on this mooring:

Instrument type Serial Number Data start (UT) Data end (UT) Instrument depth (m)
Sea Bird SBE39 1311 2011-03-25 22:00:00 2013-03-31 11:00:00 1244
Aquadopp 6000 2011-03-25 22:00:00 2013-03-31 10:45:01 1450
Sea Bird SBE37 2707 2011-03-25 22:00:01 2013-03-31 11:00:01 1450
Aquadopp 6251 2011-03-25 22:00:00 2013-03-31 10:44:59 1705
Sea Bird SBE37 7384 2011-03-25 22:00:01 2013-03-31 10:45:01 1733
Aanderaa RCM11 592 2011-03-27 04:00:05 2012-06-27 22:16:41 2900
Aanderaa RCM11 532 2011-03-27 04:00:00 2012-07-25 21:03:05 2194

Other Series linked to this Data Activity - 1618210 1223477 1362822 1223489 1223490

Cruise

Cruise Name JR20110319 (JR252, JR254C)
Departure Date 2011-03-19
Arrival Date 2011-04-06
Principal Scientist(s)Povl Abrahamsen (British Antarctic Survey)
Ship RRS James Clark Ross

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameOrkney Passage OP4
CategoryOffshore location
Latitude60° 35.38' S
Longitude41° 49.78' W
Water depth below MSL2962.0 m

Orkney Passage OP4 site

Site OP4 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 2011 but throughout the years it has been moved. The recovery/deployment history, including position details, is presented below:

Deployed Recovered
Year Cruise Year Cruise Latitude (+veN) Longitude (+ve E) Water Depth (m)
2011 JR20110319 (JR252, JR254C) 2013 JR20130317 (JR272B, JR273A, JR281, UKD-4) -60.5896 -41.8296 2962
2013 JR20130317 (JR272B, JR273A, JR281, UKD-4) 2015 JR20150309 (JR272D, JR310) -60.5898 -41.8294 2949
2015 JR20150309 (JR272D, JR310)     -60.5906 -41.8292 2972

Detailed information for each deployment can be accessed from the OP4 Data Activity document.

Other Series linked to this Fixed Station for this cruise - 1223477 1223489 1223490 1362822 1618210


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain