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Metadata Report for BODC Series Reference Number 1193148


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 Dr Gerard McCarthy
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Online delivery of data Download not available
Project(s) RAPIDMOC
RAPID-WATCH
 

Data Identifiers

Originator's Identifier OS75_DI382_NNX_SPD
BODC Series Reference 1193148
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2012-10-09 14:58
End Time (yyyy-mm-dd hh:mm) 2012-11-23 12:20
Nominal Cycle Interval 300.0 seconds
 

Spatial Co-ordinates

Start Latitude 48.07010 N ( 48° 4.2' N )
End Latitude 27.10470 N ( 27° 6.3' N )
Start Longitude 6.79360 W ( 6° 47.6' W )
End Longitude 76.61100 W ( 76° 36.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 29.23 m
Maximum Sensor or Sampling Depth 1053.29 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution Sensor fixed with measurements made at multiple depths within a fixed range (e.g. ADCP) - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)
Sensor or Sampling Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

BODC CODERankUnitsTitle
BINNUMBR0DimensionlessBin number
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ACYCAA011DimensionlessSequence number
ALATGP011DegreesLatitude north relative to WGS84 by unspecified GPS system
ALONGP011DegreesLongitude east relative to WGS84 by unspecified GPS system
APEWZZ011Centimetres per secondEastward velocity of measurement platform relative to ground surface
APNSZZ011Centimetres per secondNorthward velocity of measurement platform relative to ground surface
DBINAA012MetresDepth (spatial coordinate) of ADCP bin relative to water surface {bin depth} in the water body
LCEWAS012Centimetres per secondEastward velocity of water current (Eulerian measurement) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCNSAS012Centimetres per secondNorthward velocity of water current (Eulerian measurement) in the water body by shipborne 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


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

RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.

Long-Range Mode
Vertical Resolution Cell Size3 Max. Range (m)1 Precision (cm/s)2
8m 520 - 650 30
16m 560 - 700 17
High-Precision Mode
Vertical Resolution Cell Size3 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

  • Velocity long-term accuracy (typical): ±1.0%, ±0.5cm/s
  • Velocity range: -5 to 9m/s
  • # of depth cells: 1 - 128
  • Max ping rate: 0.7

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)

  • Range: -5° to 45°C
  • Precision: ±0.1°C
  • Resolution: 0.03°

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

RAPID cruise D382 75kHz Shipboard ADCP data processing

Originator's processing

The following was taken from the D382 cruise report. For more detailed information please refer to McCarthy (2012).

The instrument has a 30-degree beam angle and can either run in narrow-band or broad-band mode. Data were logged on a PC using the software package VmDas, with the recording stopped and re-started once a day. The instrument was configured to sample over two second intervals, with 65 bins each of 16m distance and a blank distance of 8m. For most of the cruise the instrument was run in narrow-band mode, with bottom tracking off.

The final processing was done using the CODAS (Common Ocean Data Access System) suite provided by the University of Hawaii. A summary of the steps performed is given below. For more detail refer to McCarthy (2012).

  • Initial processing - Load the data into a directory tree and make an estimate of the water track, and if available, bottom track calibrations.

  • Manual editing with gautoedit - The data are visualised and bad profiles and/or bins are removed manually.

  • Time-dependent heading correction - Correct for the time-dependent correction of the gyro with a secondary heading source, in this case the Ashtech ADU2 unit. Typically the rotation angles are of magnitude 1° or less.

  • Constant heading correction - Bottom track data is used to calculate the constant heading correction. For this cruise, bottom track data could only be acquired on the first day and the day the ship departed Santa Cruz.

  • Creating output files - After all processing steps are performed, the data are converted into two netCDF files and then merged together. The individual files are then appended to create one file for the entire cruise.

  • Missing heading information - Due to a power failure on 31/10/12, heading information was no longer coming through to VmDas. Alternate files were used to retrieve the heading information until the connection was repaired on the 06/11/12.

  • Gaps in the data - The table below summarises the reasons for missing data

    Time period (jday) Reason for missing data
    288.8-289.4 ADCP stopped
    291.3-294.5 In port at Santa Cruz
    295.7-296.3 Output .ENX and .ENS files not written, reason unknown
    303.4-307.5 Bad weather
    310.6-311.4 Fixing of missing heading data problem
    311.7-312.5 Output .ENX and .ENS files not written, reason unknown

References

McCarthy, G. et al ' RRS Discovery Cruise 382, 08 Oct - 24 Nov 2012. RAPID moorings cruise report. Southampton, UK: National Oceanography Centre, Southampton, 196pp, National Oceanography Centre Cruise Report, No 21.'

BODC processing

The data were converted from Mstar format into BODC internal format, a netCDF subset, to allow use of in-house visualisation tools. The table below shows the mapping of originator variables to BODC Parameter codes.

Originator's variable Units Description BODC Parameter Code Units Comments
lon Degrees Longitude ALONGP01 Degrees -
lat Degrees Latitude ALATGP01 Degrees -
depth (of bin) m Depth of ADCP bin DBINAA01 m -
uabs cm s-1 Absolute Eastward current velocity LCEWAS01 cm s-1 -
vabs cm s-1 Absolute Northward current velocity LCNSAS01 cm s-1 -
uship m s-1 Ship's Eastward velocity APEWGP01 cm s-1 Values converted by multiplication by 100.
vship m s-1 Ship's Northward velocity APNSGP01 cm s-1 Values converted by multiplication by 100.
speed cm s-1 Scalar current speed - - Variable not transferred. Superseded by vector values
shipspd cm s-1 Scalar ship speed - - Variable not transferred. Superseded by vector values

Reformatted data were visually checked using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

Once quality control screening was complete, the data were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.


Project Information

Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)

Scientific Rationale

There is a northward transport of heat throughout the Atlantic, reaching a maximum of 1.3PW (25% of the global heat flux) around 24.5°N. The heat transport is a balance of the northward flux of a warm Gulf Stream, and a southward flux of cooler thermocline and cold North Atlantic Deep Water that is known as the meridional overturning circulation (MOC). As a consequence of the MOC northwest Europe enjoys a mild climate for its latitude: however abrupt rearrangement of the Atlantic Circulation has been shown in climate models and in palaeoclimate records to be responsible for a cooling of European climate of between 5-10°C. A principal objective of the RAPID programme is the development of a pre-operational prototype system that will continuously observe the strength and structure of the MOC. An initiative has been formed to fulfill this objective and consists of three interlinked projects:

  • A mooring array spanning the Atlantic at 26.5°N to measure the southward branch of the MOC (Hirschi et al., 2003 and Baehr et al., 2004).
  • Additional moorings deployed in the western boundary along 26.5°N (by Prof. Bill Johns, University of Miami) to resolve transport in the Deep Western Boundary Current (Bryden et al., 2005). These moorings allow surface-to-bottom density profiles along the western boundary, Mid-Atlantic Ridge, and eastern boundary to be observed. As a result, the transatlantic pressure gradient can be continuously measured.
  • Monitoring of the northward branch of the MOC using submarine telephone cables in the Florida Straits (Baringer et al., 2001) led by Dr Molly Baringer (NOAA/AOML/PHOD).

The entire monitoring array system created by the three projects will be recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2014 the array will continue to be serviced annually under RAPID-WATCH funding.

The array will be focussed on three regions, the Eastern Boundary (EB), the Mid Atlantic Ridge (MAR) and the Western Boundary (WB). The geographical extent of these regions are as follows:

  • Eastern Boundary (EB) array defined as a box with the south-east corner at 23.5°N, 25.5°W and the north-west corner at 29.0°N, 12.0°W
  • Mid Atlantic Ridge (MAR) array defined as a box with the south-east corner at 23.0°N, 52.1°W and the north-west corner at 26.5°N, 40.0°W
  • Western Boundary (WB) array defined as a box with the south-east corner at 26.0°N, 77.5°W and the north-west corner at 27.5°N, 69.5°W

References

Baehr, J., Hirschi, J., Beismann, J.O. and Marotzke, J. (2004) Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. Journal of Marine Research, Volume 62, No 3, pp 283-312.

Baringer, M.O'N. and Larsen, J.C. (2001) Sixteen years of Florida Current transport at 27N Geophysical Research Letters, Volume 28, No 16, pp3179-3182

Bryden, H.L., Johns, W.E. and Saunders, P.M. (2005) Deep Western Boundary Current East of Abaco: Mean structure and transport. Journal of Marine Research, Volume 63, No 1, pp 35-57.

Hirschi, J., Baehr, J., Marotzke J., Stark J., Cunningham S.A. and Beismann J.O. (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophysical Research Letters, Volume 30, No 7, article number 1413 (DOI 10.1029/2002GL016776)


RAPID- Will the Atlantic Thermohaline Circulation Halt? (RAPID-WATCH)

RAPID-WATCH (2007-2014) is a continuation programme of the Natural Environment Research Council's (NERC) Rapid Climate Change (RAPID) programme. It aims to deliver a robust and scientifically credible assessment of the risk to the climate of UK and Europe arising from a rapid change in the Atlantic Meridional Overturning Circulation (MOC). The programme will also assess the need for a long-term observing system that could detect major MOC changes, narrow uncertainty in projections of future change, and possibly be the start of an 'early warning' prediction system.

The effort to design a system to continuously monitor the strength and structure of the North Atlantic MOC is being matched by comparative funding from the US National Science Foundation (NSF) for the existing collaborations started during RAPID for the observational arrays.

Scientific Objectives

  • To deliver a decade-long time series (2004-2014) of calibrated and quality-controlled measurements of the Atlantic MOC from the RAPID-WATCH arrays.
  • To exploit the data from the RAPID-WATCH arrays and elsewhere to determine and interpret recent changes in the Atlantic MOC, assess the risk of rapid climate change, and investigate the potential for predictions of the MOC and its impacts on climate.

This work will be carried out in collaboration with the Hadley Centre in the UK and through international partnerships.

Mooring Arrays

The RAPID-WATCH arrays are the existing 26°N MOC observing system array (RAPIDMOC) and the WAVE array that monitors the Deep Western Boundary Current. The data from these arrays will work towards meeting the first scientific objective.

The RAPIDMOC array consists of moorings focused in three geographical regions (sub-arrays) along 26.5° N: Eastern Boundary, Mid-Atlantic Ridge and Western Boundary. The Western Boundary sub-array has moorings managed by both the UK and US scientists. The other sub-arrays are solely led by the UK scientists. The lead PI is Dr Stuart Cunningham of the National Oceanography Centre, Southampton, UK.

The WAVE array consists of one line of moorings off Halifax, Nova Scotia. The line will be serviced in partnership with the Bedford Institute of Oceanography (BIO), Halifax, Canada. The lead PI is Dr Chris Hughes of the Proudman Oceanographic Laboratory, Liverpool, UK.

All arrays will be serviced (recovered and redeployed) either on an annual or biennial basis using Research Vessels from the UK, US and Canada.

Modelling Projects

The second scientific objective will be addressed through numerical modelling studies designed to answer four questions:

  • How can we exploit data from the RAPID-WATCH arrays to obtain estimates of the MOC and related variables?
  • What do the observations from the RAPID-WATCH arrays and other sources tell us about the nature and causes of recent changes in the Atlantic Ocean?
  • What are the implications of RAPID-WATCH array data and other recent observations for estimates of the risk due to rapid change in the MOC?
  • Could we use RAPID-WATCH and other observations to help predict future changes in the MOC and climate?

Data Activity or Cruise Information

Cruise

Cruise Name D382
Departure Date 2012-10-08
Arrival Date 2012-11-24
Principal Scientist(s)Gerard McCarthy (National Oceanography Centre, Southampton)
Ship RRS Discovery

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
Q value below limit of quantification