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Metadata Report for BODC Series Reference Number 1805705


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI Workhorse Monitor 300 kHz direct-reading ADCP  current profilers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Mr Povl Abrahamsen
Originating Organization British Antarctic Survey
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) BAS Long Term Monitoring and Survey
 

Data Identifiers

Originator's Identifier JR310M003
BODC Series Reference 1805705
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2015-03-18 22:21
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 9.7 metres
 

Spatial Co-ordinates

Latitude 62.55769 S ( 62° 33.5' S )
Longitude 42.93939 W ( 42° 56.4' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 9.59 m
Maximum Sensor or Sampling Depth 3012.51 m
Minimum Sensor or Sampling Height 64.98 m
Maximum Sensor or Sampling Height 3067.91 m
Sea Floor Depth 3077.5 m
Sea Floor Depth Source GEBCO1401
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Chart reference - Depth extracted from available chart
 

Parameters

BODC CODERankUnitsTitle
ACYCAA011DimensionlessSequence number
ADEPZZ011MetresDepth (spatial coordinate) relative to water surface in the water body
LCEWLW011Centimetres per secondEastward velocity of water current (Eulerian measurement) in the water body by lowered acoustic doppler current profiler (ADCP)
LCNSLW011Centimetres per secondNorthward velocity of water current (Eulerian measurement) in the water body by lowered acoustic doppler current profiler (ADCP)

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

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): Data Quality Report

The LADCP was used in all CTD stations, except for cast 51 due to the high depth reached in this station. No file was generated.

The orignator noted there was no evident issue during the processing of most of the stations, with the data looking reasonably good. On stations 14 and 58 the ADCP did not detect the bottom correctly; this problem was overcome by forcing the software to use its own bottom track/ranges. On station 14 the bottom detection still did not work as intended, and the bottom depth needed to be set manually in Matlab. All other casts ran as intended,without any need for manual intervention by the originator.


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

Teledyne RDI's Workhorse Monitor ADCP

The Workhorse Monitor acoustic doppler current profler (Teledyne RD Instruments) is a long-range and long-term self contained ADCP. It has a patented four beam signal (300, 600 or 1200 kHz) and a standard depth rating of 200m or 600m. It operates effectively between temperatures of -5°C and 45°C and has a velocity accuracy of ±1% ±5mm/s.

RRS James Clark Ross JR20150309 (JR272D, JR310) CTD Instrumentation

A Sea-Bird 911 plus CTD system was used on cruise JR20150309 (JR272D, JR310). This was mounted on a SBE-32 carousel water sampler holding 24 12-litre Niskin bottles. The CTD was fitted with the following scientific sensors:

Sensor Serial Number Calibration Date Comments
Sea-Bird SBE 3plus (SBE 3P) temperature sensor 5043 08 May 2014 Primary sensor
Sea-Bird SBE 3plus (SBE 3P) temperature sensor 2307 07 May 2014 Secondary sensor
Sea-Bird SBE 4C conductivity sensor 3419 23 April 2014 Primary sensor
Sea-Bird SBE 4C conductivity sensor 4090 23 April 2014 Secondary sensor
Sea-Bird SBE 9plus CTD 0541 21 May 2014 -
Sea-Bird SBE 43 Dissolved Oxygen Sensor 0620 02 May 2014 -
Sea-Bird SBE 35 thermometer 0051 14 May 2014 -
Chelsea Technologies Group Aquatracka III fluorometer 7235 24 March 2013 -
WETLabs C-Star transmissometer CST-1479DR 02 June 2014 -
Biospherical QCP-2200 underwater PAR sensor 7235 24 April 2013 -
Tritech PA-200 Altimeter 10127.244739 Unavailable -

A single Teledyne RDI 300kHz Workhorse Monitor direct-reading ADCP was also fitted to the CTD frame.

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): BODC Processing

LADCP processed matlab files were converted into a BODC internal NetCDF format. The following table shows how the variables were mapped to appropriate BODC parameter codes:

Originator's Parameter Name Units Description BODC Parameter Code Units Comments
z m Depth below surface of the water body ADEPZZ01 m -
u m s-1 Eastward current velocity (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP) LCEWLW01 cm s-1 Units converted from m s-1 to cm s-1 by multiplying by 100.
v m s-1 Northward current velocity (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP) LCNSLW01 cm s-1 Units converted from m s-1 to cm s-1 by multiplying by 100.

All reformatted data were visualised using the in-house Edserplo software and screened for suspect and missing data.

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): Originator's processing

Sampling strategy

A single RDI 300-kHz Workhorse Monitor LADCP was mounted on the CTD frame in a downward-facing orientation and was deployed on all 74 CTD casts, however was switched off for CTD cast 51 due to the deep depth of the station. The instrument was configured to record 16 depth bins in a 10m bin length, in a narrow bandwidth with 5m blanking distance. Before each cast was deployed, a pre-deployment test script was run to verify that the internal electronics were performing correctly. Both the test script and deployment script are outlined in detail in the cruise report.

Data processing

The binary files recorded by the instrument, together with the log files, were downloaded to the local computer and copied to the server after each cast. The data were processed using a package fully written in Matlab code, originally developed at Lamont-Doherty Earth Observatory (LDEO) by Martin Visbeck and updated by Andreas Thurnherr (version LDEO IX_10). This package calculates velocity based both on the velocity inversion and shear methods.

Modifications to the set_cast_params.m script were made by Marina Azaneu and Povl Abrahamsen to load CTD, GPS, and SADCP data from the JCR. This created files containing CTD time series and CTD profile data from the mstar-processed CTD data with resolution of 1 Hz and averaged into 2 dbar, respectively. GPS time series were also generated during the processing (based on the 1-Hz CTD data), in addition to SADCP time series. These auxiliary data are not required for the LADCP processing, but are essential for acquiring better quality results.

Two main modifications were applied to the original scripts. Firstly, it was noticed that if the same station were processed twice, there was a conflict when the software overwrites the created auxiliary data, CTD time series, CTD profile data, navigation datam, SADP time series, leading to unreasonable results. Thus, the script was modified to verify the existence of these files and delete them before creating the new files. The second modification regards the SADCP data, which were considered too noisy in some stations. After testing different thresholds, it was defined that only SADCP data with percent good higher than 25% would be used for the LADCP processing. Both modifications are included on the set_cast_params.m file.


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:

  • Topographic survey
  • Geosciences survey
  • Biological survey and monitoring
  • Atmospheric and oceanographic monitoring

Data Availability

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


Data Activity or Cruise Information

Cruise

Cruise Name JR20150309 (JR272D, JR310)
Departure Date 2015-03-09
Arrival Date 2015-04-14
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
B nominal value
Q value below limit of quantification