Metadata Report for BODC Series Reference Number 1223140


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI Ocean Surveyor 75kHz vessel-mounted ADCP  current profilers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr Hugh Venables
Originating Organization British Antarctic Survey
Processing Status QC in progress
Project(s) Polar Oceans
 

Data Identifiers

Originator's Identifier JR239_LADCP
BODC Series Reference 1223140
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-03-20 09:32
End Time (yyyy-mm-dd hh:mm) 2010-04-23 23:53
Nominal Cycle Interval 600.0 seconds
 

Spatial Co-ordinates

Start Latitude 39.78420 S ( 39° 47.1' S )
End Latitude 51.66020 S ( 51° 39.6' S )
Start Longitude 56.06040 W ( 56° 3.6' W )
End Longitude 57.64560 W ( 57° 38.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 22.7 m
Maximum Sensor Depth 1054.3 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Scattered at fixed depths - The sensors are scattered with respect to depth but each remains effectively at the same depth for the duration of the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

No Parameters for BODC Reference Number = 1223140

 

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 Quality Report

The data become more sparse the deeper the bin depth, with very few data cycles between bin number 47 and 58, after which there are no data. 70 bins were used, however, bins 66 to 70 did not contain any bin depths or data.

Note that there are changes in the bin depths and bin widths during the periods 20 March 2010 09:32:07 hours to 20 March 2010 12:50:47 hours, 22 March 2010 11:40:05 hours to 23 March 2010 09:33:35 hours and between 29 March 2010 03:46:07 hours and 29 March 2010 10:39:36 hours. These are related to changes in the LADCP settings which are detailed the Originator's Data Processing section and thecruise report.


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

Instrument Description

A 75 kHz Teledyne RD Instruments Ocean Surveyor acoustic doppler current profiler (ADCP) fitted to the hull of the RSS James Clark Ross was used. The ship's hull depth is 6.47 m, the transducer depth is 6.3 m, the distance of the transducer behind the seachest window is 100-200 mm and the window thickness is 50 mm. The design draft of the ship is 6.3 m, which is subject to slight changes depending on load, with full load the draft is 6.4 m.

The navigation data was input from the Kongsberg Seatex Seapath 200 Global Positioning System receiver and Gyrocompass.

ADCP setup, data logging, preliminary screening and mapping of beam data onto Earth coordinates was done with RDI VmDas software, version 1.42.

RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.

Long-Range Mode
Vertical Resolution Cell Size 3 Max. Range (m) 1 Precision (cm/s) 2
8m 520 - 650 30
16m 560 - 700 17
High-Precision Mode
Vertical Resolution Cell Size 3 Max. Range (m) 1 Precision (cm/s) 2
8m 310 - 430 12
16m 350 - 450 9

1 Ranges at 1 to 5 knots ship speed are typical and vary with situation.
2 Single-ping standard deviation.
3 User's choice of depth cell size is not limited to the typical values specified.

Profile Parameters

Bottom Track

Maximum altitude (precision <2cm/s): 950m

Echo Intensity Profile

Dynamic range: 80dB
Precision: ±1.5dB

Transducer and Hardware

Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W

Standard Sensors

Temperature (mounted on transducer)

Environmental

Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*

*later instruments have greater range.

Web Page

Further details can be found on the manufacturer's website or in the specification sheet

BODC Processing

The data were received in one Matlab formated file and were converted into BODC internal format following BODC's standard procedures. Tidal model predictions and de-tided data were also provided but have not been loaded as these are subjective calculations, these are available on request. The following table shows how the variables within the Matlab file were mapped to appropriate BODC parameter codes.

Originator's Parameter Name Units Description BODC Parameter Code Units Comments
depth m ADEPZZ01 Depth below surface of the water body for each bin m Bin depth was changed during cruise
lat Degrees ALATGP01 Latitude - -
lon Degrees ALONGP01 Longitude - -
u m s -1 LCEWAS01 Eastward current velocity (Eulerian) in the water body - -
v m s -1 LCNSAS01 Northward current velocity (Eulerian) in the water body - -
vtide m s -1 Tidal model prediction northward velocity - - -
utide m s -1 Tidal model prediction eastward velocity - - -
udetide m s -1 Eastward velocity with tidal prediction removed - - -
vdetide m s -1 Northward velocity with tidal prediction removed - - -

All reformatted data were visualised using the in-house Edserplo software, all suspect and null data were flagged as such.

Originator's Data Processing

Sampling Strategy

The vessel mounted 75 kHz RD Instruments Ocean Surveyor ADCP was configured to sample over 70 bins. Five settings were used during the cruise:
1) Narrowband with Bottom Tracking on, maximum bin depth 500 m.
2) Narrowband with Bottom Tracking on, maximum bin depth 1000 m.
3) Narrowband with Bottom Tracking off, maximum bin depth 1000 m.
4) Broadband with Bottom Tracking on, maximum bin depth set to 200 m.
5) Broadband with Bottom Tracking on, maximum bin depth set to 500 m.

The bin size was set to 8 m in broadband and 16 m in narrowband mode and the blanking distance at the surface was set to 8 m. The narrowband mode with and without bottom tracking was mostly used during the cruise. An overview of the available commands to set the ADCP operating parameters and the command files for the narrowband modes to 1000 m used during the cruise can be found in the cruise report page 121.

Originators Data Processing

The ADCP was controlled using the proprietary RDI VmDas software, version 1.42, this was used for; data acquisition, archiving, processing, displaying, and reporting, in addition, a set of Matlab routines were used for the post-processing of the VmDas data. Extensive processing methods can be found in the cruise report page 99 onwards.

To summarise, the ADCP was fed with the navigation and attitude data from the Kongsberg Seatex Seapath 200 GPS system with bad navigation removed. The distance and the direction between navigation fixes were calculated and then converted to distance in eastward and northward direction, and filtered to remove spikes from the navigation. The water and bottom track velocities were scaled and corrected for misalignment, and the horizontal velocities were multiplied by the scaling factor and rotated by the specified misalignment angle. The heading was adjusted by subtracting the misalignment angle. For sequences recorded in bottom track mode, the bottom range was used to blank the data below 86% of the detected bottom depth.

Bad data points from interference, bubbles, outliers etc. were filtered using various criteria:
1) Velocities greater than 1.5 m s -1 .
2) Absolute values of velocity exceeded ±2 times the standard deviation of the error velocity provided through the fourth beam.
3) Velocities outside running average velocity ±2 time standard deviation or running median velocity ± 2 times standard deviation.
4) Changes in ship speed exceeded the maximum ship velocity change of 0.5514 m per ping.
5) Change in heading exceeded the maximum heading velocity change of 10°.
6) The velocities of ping ensembles with the percentage of good four beam solutions equal to zero.

To get usable data, 10 minute averages from the clean, filtered data were calculated taking into account varying bin depths (see the cruise report for details of how averaging was carried out).

Preliminary de-tiding was done for the final 10 minute averages using the tide model 'AntPen'. These data are available on request.

Field Calibrations

The calibration points were extracted using 2 minute averages (see cruise report for details of how the averaging was carried out) of ADCP data meeting the following criteria;
1) Change in ship heading is small.
2) Change in ship speed is small.
3) Ship speed is within the interval average ship speed ± standard deviation.
4) Ship heading is within the interval average ship heading ± standard deviation.
5) Bottom speed is larger than a specified minimum speed.
6) There are a minimum number of possible calibration points in a row that fulfill the criteria.

The calibration was done for the entire cruise using water track calibration. Although bottom track data were collected, most of the cruise took place in deep water, and the available bottom track was not sufficient and so bottom track calibration was not satisfactory.

Misalignment angle (φ): -0.0748
Amplitude (α): 1.015741

Further information on calibration of the VMADCP can be found on page 114 of the cruise report.


Project Information

Polar Oceans

Introduction

The Polar Oceans programme is a British Antarctic Survey (BAS) core quinquennial research programme, funded by the Natural Environment Research Council (NERC), that started in 2009. It contributes to the NERC's Science Themes on Earth System Science, Climate, particularly the Earth System Science sub-challenges on ocean processes and their interaction with the Earth System, and global biogeochemical cycling; and the Climate challenge to improve understanding of the changing water cycle and how it will affect water availability and quality.

This programme will investigate the role of processes and changes both in the shelf sea and in open-ocean environments, and will contribute to the understanding of polar control of Earth System. The instruments and techniques used in this programme include the deployment of oceanographic moorings beneath ice shelves, using hot water drill technology, in the Weddell, Amundsen and Bellingshausen Seas, sustained high-frequency oceanographic observation at the Antarctic Peninsula and the combination of repeat hydrography and moorings.

The main objectives are:

The Polar Oceans programme has links to several national and international initiatives:

Data Availability

The data produced during this project are available to the academic community.


Data Activity or Cruise Information

Cruise

Cruise Name JR20100319 (JR235, JR236, JR239)
Departure Date 2010-03-19
Arrival Date 2010-04-24
Principal Scientist(s)Mike Meredith (British Antarctic Survey)
Ship RRS James Clark Ross

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameWOCE section A23
CategoryOffshore route/traverse

WOCE Hydrographic Programme Section A23

This section is part of the One-Time Survey of World Ocean Circulation Experiment (WOCE) designated A23. A hydrographic section from Antarctica to Brazil in the South West Atlantica. A full suite of physical, chemical, biological, meterological and tracer measurements were made. During WOCE in 1995 (James Clark Ross, cruise JR10) the A23 section area encompassed 20-70° S and 20-70° S. Part of this A23 section located in the eastern Scotia Sea has been repeated by the ALBATROSS project (James Clark Ross, cruise JR40) in 1999, the US CLIVAR repeat hydrography/CO2 in 2005 (R/V Ronald H. Brown, cruise A16S_2005a) under the CLIVAR/Carbon repeat hydrography program. From 2010 onwards the British Antarctic Survey has conducted annual cruises to survey the southern portion of this section, from the Weddell Sea to South Georgia. A comprehensive list of cruises is included below the map.

From

BODC image

History of Occupations at Section A23

Cruise Start Date End Date Country PSO
James Clark Ross JR19950320 (JR10) 20-04-1995 06-06-1995 United Kingdom K. Heywood
James Clark Ross JR19990315 (JR40) 15-03-1999 22-04-1999 United Kingdom K. Heywood
Ronald H. Brown A16S_2005a 11-01-2005 24-02-2005 United States R. Wanninkhof
James Clark Ross JR20100319 (JR235, JR236, JR239) 19-03-2010 24-04-2010 United Kingdom M. Meredith
James Clark Ross JR20120327 (JR254E, JR257, JR272A) 27-03-2012 24-04-2012 United Kingdom Hugh Venables
James Clark Ross JR20130317 (JR252B, JR272B, JR273A, JR281, UKD-4) 17-03-2013 27-04-2013 United Kingdom Jean Baptiste Sallee
James Clark Ross JR20140331 (JR272C, JR273B, JR293 Leg2, JR299 Leg 2, UKD-5) 31-03-2014 29-04-2014 United Kingdom Andrew Meijers
James Clark Ross JR20150309 (JR272D, JR310) 09-03-2015 14-04-2015 United Kingdom Povl Abrahamsen
James Clark Ross JR15006 31-03-2016 26-04-2016 United Kingdom Andrew Meijers
James Clark Ross JR16004 24-01-2017 13-03-2017 France Jean Baptiste Sallee

Other Series linked to this Fixed Station for this cruise - 1046591 1046609 1046610 1046622 1046634 1046646 1046658 1046671 1046683 1046695 1046702 1046714 1046726 1046738 1046751 1046763 1046775 1046787 1046799 1046806 1046818 1046831 1046843 1046855 1046867 1046879 1046880

Other Cruises linked to this Fixed Station (with the number of series) - JR15006 (57) JR20120327 (JR254E, JR257, JR272A) (20) JR20130317 (JR252B, JR272B, JR273A, JR281, UKD-4) (59) JR20140309 (JR293 Leg1, JR299 Leg1, UKD-5) (21)


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