Metadata Report for BODC Series Reference Number 1368805


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Aanderaa RCM 7/8 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 CI1_0607_4_RCM8_12677_3378M
BODC Series Reference 1368805
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-12-27 02:00
End Time (yyyy-mm-dd hh:mm) 2007-02-24 14:46
Nominal Cycle Interval 3600.0 seconds
 

Spatial Co-ordinates

Latitude 60.27284 S ( 60° 16.4' S )
Longitude 45.26256 W ( 45° 15.8' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 3378.0 m
Maximum Sensor Depth 3378.0 m
Minimum Sensor Height 600.0 m
Maximum Sensor Height 600.0 m
Sea Floor Depth 3978.0 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 Instantaneous - Depth measured below water line or instantaneous water body surface
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
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
PREXPR01 1 Decibars MeasPress_MW Pressure (measured variable) exerted by the water body by semi-fixed in-situ pressure sensor and corrected to read zero at sea level
TEMPPR01 1 Degrees Celsius Temp Temperature of the water body
 

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 7/8

Manufacturer's specifications: recording unit height 49.5cm (RCM8 52.0cm), diameter 12.8cm, vane size 48.5x50.0cm. Meter is designed for depths down to 2000m (RCM8 6000m). It incorporates a spindle which is shackled to the mooring line. The meter is attached to the spindle through a gimbal mounting which permits a maximum 27° deviation of the spindle from the vertical, the meter still remaining horizontal.

Meter comprises :

  1. Paddle wheel rotor magnetically coupled to an electronic counter

  2. Vane, which aligns instrument with current flow, has a balance weight ensuring static balance and tail fins to ensure dynamic balance in flows up to 250cm/s.

  3. Magnetic compass (needle is clamped to potentiometer ring) - direction recorded with 0.35° resolution, 5° accuracy for speeds 5 to 100cm/s, 7.5° accuracy for remaining speeds within 2.5 to 200cm/s range.

  4. Quartz clock, accuracy better than 2 sec/day within temperature range 0 to 20°C.

  5. Thermistor (temperature sensor), standard range -2.46 to 21.48°C (max on high range 36.04°C), accuracy 0.05°C, resolution 0.1 per cent of range, 63 per cent response time 12sec.

  6. Inductive cell conductivity sensor (optional), range 0 to 70mmho/cm standard resolution 0.1 per cent of range.

  7. Silicon piezoresistive bridge, standard range 0 to 3000 psi (RCM8 to 9000 psi), resolution 0.1% of range.

  8. Self balancing potentiometer which converts the output from each sensor into a 10 bit binary number for storage on magnetic tape.

  9. Associated electronics.

A built-in clock triggers the instrument at preset intervals and up to six channels are sampled in sequence. Channel 1 is a fixed reference reading for control purposes and data identification. Channels 2, 3 and 4 represent measurement of temperature, conductivity and pressure. Channels 5 and 6 represent the VECTOR AVERAGED current speed and direction since the previous triggering of the instrument. The number of rotor revolutions and the direction is sampled every 12 seconds and broken into North and East components. Successive components are added and recorded as speed and direction. For recording intervals longer than 10 minutes, speed and direction are sampled 1/50th of recording interval.

It has become common practice in some laboratories to deploy these meters as temperature and conductivity loggers without current measuring capabilities.

The following link will provide the manufacturer specifications:

Manufacturer specifications

BODC Processing

Data Processing

The data arrived at BODC in Matlab format representing data collected from moorings CI1, CI2, OP1, OP2, OP3, OP5 and OP6. Data were obtained from a total of five different types of instruments, RCM8, RCM11, SBE37, SBE39 and Aquadopps.

Reformatting

The RCM 8 files were reformatted to an internal format using BODC established procedures. The parameters which were not reformatted include botdepth, date, latitude, longitude, mooring name, nomdepth (m), serial_no and type as these constitute metadata and not environmental data, however, these variables are available upon request.

The table below illustrates how the originator's variables within the .MAT files were mapped to the appropriate BODC parameter codes:

Originators Variable Name Units Description BODC Parameter Code Units
temp °C The degree of hotness of the water column expressed against a standard scale. Includes both IPTS-68 and ITS-90 scales. TEMPPR01 degC
speed cm s -1 Current speed (Eulerian) in the water body. The speed of Eulerian flow in the water column. LCSAZZ01 cm s -1
press dbar Pressure (measured variable) exerted by the water body by semi-fixed in-situ pressure sensor and corrected to read zero at sea level. PREXPR01 dbar
u cm s -1 Eastward current velocity (Eulerian) in the water body by in-situ current meter. LCEWZZ01 cm s -1
v cm s -1 Northward current velocity (Eulerian) in the water body by in-situ current meter. LCNSZZ01 cm s -1
dir deg Current direction in the water body. The direction towards which Eulerian current in the water column is flowing. LCDAZZ01 deg

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

Note that PREXPR01 is only present in series reference: 1368805, 1368830, 1368842 and 1368878.

Screening

The data were visualised using in house software and quality flags were applied to any improbable data.

Originators 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 CI1, CI2, OP3 and OP5 which were equipped with RCM8 current meters were first deployed in 2011. Data collection is currently ongoing as part of the BAS LTMS project with measurements acquired on a 60 minute basis

Gaps in the data series may be due to measurements not being obtained, instrument malfunction and/or the instruments not being recovered.

Data Processing:

Little information is known with regards to the exact details of calibrations carried out on the mooring data. Originators data processing, visualisation and calibration were completed using Matlab version R2014b using a script created by the originator. The calibration, which was applied to the raw data, corrected, plot overview figures and thus exported a final Matlab data version which was transferred by BODC. However, the current velocity and direction components have not been corrected for magnetic variation. This is due to the variation in this region being less than one degree, which is less than the accuracy of the current direction measurements of the instrument.

An offset value has been applied to the corrected/calibrated temperature variables, the offset values applied can be found below:

Mooring Time Period (UT) Depth Serial Number Offset Applied
CI1 27/12/2005 - 24/02/2007 3378m 12677 0.0400
CI2 26/12/2005 - 24/02//2007 3382m 12669 0.0400
OP3 25/02/2007 - 28/02/2009 1989m 12669 0.0400
OP3 25/02/2007 - 28/02/2009 1833m 12677 0.0400
OP3 02/03/2009 - 25/03/2011 1966m 12669 0.0150
OP3 02/03/2009 - 25/03/2011 1966m 12677 0.0150
OP5 27/03/2011 - 29/03/2013 2986m 12677 0.0150
OP5 27/03/2011 - 29/03/2013 3343m 12669 0.0150

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) 2005-12-27
End Date (yyyy-mm-dd) 2007-02-24
Organization Undertaking ActivityBritish Antarctic Survey
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierCI
Platform Categorysubsurface mooring

Coronation Island mooring 1

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 CI1
Platform Category Subsurface mooring
Latitude (+ve N) -60.2728
Longitude (+ve E) -45.2626
Water Depth (m) 3912

The mooring was deployed off Coronation Island on cruise JR20051226 (JR151) on 27 December 2005 and recovery was done on cruise ES20070116 (ES031, ES038, ES048) on 24 February 2007.

The table below lists the instruments deployed on this mooring:

Instrument type Serial Number Data start (UT) Data end (UT) Instrument depth (m)
Aanderaa RCM8 12677 2005-12-27 02:00:00 2007-02-24 14:46:00 3378
Sea Bird SBE39 110 2005-12-27 00:34:59 2007-02-24 15:49:59 3578
Aanderaa RCM11 532 2005-12-27 01:00:00 2007-02-24 14:57:00 3778
Aanderaa RCM11 517 2005-12-27 00:59:00 2007-02-24 14:49:00 3928

Data issues found at recovery

Aanderaa conductivity sensors also exhibited large jumps in two records and a rapid initial drift which the originator estimates is due to distortion/creeping to accomodate the water pressure.

Other Series linked to this Data Activity - 1618129 1618130 1223176

Cruise

Cruise Name JR20051226 (JR151)
Departure Date 2005-12-26
Arrival Date 2005-12-27
Principal Scientist(s)Povl Abrahamsen (British Antarctic Survey)
Ship RRS James Clark Ross

Complete Cruise Metadata Report is available here


Fixed Station Information


No Fixed Station Information held for the Series


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