Metadata Report for BODC Series Reference Number 1102030


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI 150kHz Narrowband Vessel-Mounted ADCP  current profilers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Brian King
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Project(s) GO-SHIP
 

Data Identifiers

Originator's Identifier OS150_DI368_ALL
BODC Series Reference 1102030
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2011-07-15 11:58
End Time (yyyy-mm-dd hh:mm) 2011-08-04 03:46
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Start Latitude 23.33220 N ( 23° 19.9' N )
End Latitude 53.56680 N ( 53° 34.0' N )
Start Longitude 27.14470 W ( 27° 8.7' W )
End Longitude 4.17570 W ( 4° 10.5' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 17.23 m
Maximum Sensor Depth 489.3 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Sensor fixed, measurements made at fixed depths - 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 Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
BINNUMBR 0 Dimensionless BinNum Bin number
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
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
APEWAS01 1 Centimetres per second PlatformVelE_GPS Eastward velocity (over ground) of measurement platform by Ashtech GPS
APNSAS01 1 Centimetres per second PlatformVelN_GPS Northward velocity (over ground) of measurement platform by Ashtech GPS
APSAZZ01 1 Metres per second Plat_speed Speed (over ground) of measurement platform
DBINAA01 2 Metres BinDep Depth below sea surface (ADCP bin)
LCEWAS01 2 Centimetres per second CurrVelE_ADCP Eastward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCNSAS01 2 Centimetres per second CurrVelN_ADCP Northward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCSAAS01 2 Centimetres per second CurrSpd_ADCP Current speed (Eulerian) 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 150kHz Narrow Band Acoustic Doppler Current Profiler

Specifications

Water velocity measurements relative to the ADCP
Accuracy (long term) 0.5 % of measured velocity ± 0.5 cm/s
Statistical uncertainty for one ping (cm/s) Depth cell length of 4, 8, 16 m = 26, 13, 6.5 respectively (for horizontal velocities using the standard transducer)
Ping rate (pings per second) 2 (100 pings averaged in ADCP)
Maximum profiling range (meters) 290
Minimum range to start of first depth cell (meters) 4
Number of depth cells 8 to 128
Velocity range ± 0.01 to 9.5 m/s (horizontal)
Velocity resolution (cm/s) 0.25 or 0.125
Velocity measurements relative to the bottom and measurement of bottom depth
Accuracy 0.5% of measured velocity ± 0.5 cm/s
Statistical uncertainty of one ping (percent of measured velocity) 3.5 (for horizontal velocities using the standard transducer)
Ping rate (pings per second) 0.9 (100 pings averaged in ADCP)
Depth range 290 (the maximum depth range can be up to 1.5 times greater than specified)
Bottom depth resolution (meters) 4
Velocity range ± 0.01 to 9.5 m/s (horizontal)
Velocity resolution (cm/s) 0.25 or 0.125
Measurement of echo intensity
Accuracy (with temperature correction) Before calibration : ± 8 dB, After calibration: ± 3 dB
Statistical uncertainty for one ping Approximately ± 5 dB
Ping rate (pings per second) 2 (100 pings averaged in ADCP)
Profiling range (meters less than for water velocity measurement) 64
Number of depth cells 8 to 128
Dynamic range 80 dB
Resolution 0.45 dB typical (temperature/system dependent)
Data communication
Interface Modified RS-232/422 serial at baud rates of 300-19,200
Data format Binary (8-bit) or ASCII (76-character) lines separated by a carriage return/line feed.
Data storage capacity 2 MB (standard); expandable to 40 MB in 1 and/or 2 MB increments
Power requirements
ADCP electronics Voltage range (VDC) 6-12; Standby current (amps) 0.0002; Operate current (amps) 0.24; Peak current (amps) 0.5
transmit and EPROM recorder Voltage range (VDC) 20-40; Standby current (amps) 0.0001; Operate current (amps) 0.10; Peak current (amps) 2.0
CTD sensors Voltage range (VDC) 12-20; Standby current (amps) 0.0001; Operate current (amps) 0.022; Peak current (amps) 0.05
Temperature sensor
Accuracy ± 0.2°C
Time constant Approximately 2 minutes
Range -5° to 45°C
Resolution 0.012°C
Environmental
Operating temperature -5°C to 40°C
Humidity Must be non-condensing
Depth capability 35 meters (transducer only)
Physical characteristics
Weight in air 67.6 kg
Weight in water 25.0
Diameter 45.9 cm
Length 141.4 cm

BODC Processing

Data were obtained using the 150 kHz Teledyne RDI Ocean Surveyor Vessel Mount Acoustic Doppler Current Profiler (ADCP), on Cruise D368. They were received at BODC in MSTAR format files.

The data were reformatted to the internal NetCDF format using BODC-generated Matlab code. The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:

Originator's variable Units Description BODC Code Units Comments
uabs cm s -1 Absolute eastward water velocity (Eulerian) by ADCP LCEWAS01 cm s -1 -
vabs cm s -1 Absolute northward water velocity (Eulerian) by ADCP LCNSAS01 cm s -1 -
time seconds - - - Not transferred - recalculated by the transfer
lon degrees Longitude east (WGS84) using unspecified GPS system ALONGP01 degrees -
lat degrees Latitude north (WGS84) using unspecified GPS system ALATGP01 degrees -
uship m s -1 Eastward velocity (over ground) of measurement platform by Ashtech GPS APEWAS01 cm s -1 conversion: multiply by 100
vship m s -1 Northward velocity (over ground) of measurement platform by Ashtech GPS APNSAS01 cm s -1 conversion: multiply by 100
depth metres ADCP bin depth (bottom of bin) DBINAA01 metres -
decday days - - - Not transferred - recalculated by the transfer
speed cm s -1 Absolute water speed (Eulerian) by ADCP LCSAAS01 cm s -1 derived from uabs and vabs
shipspd m s -1 Ship speed over the ground APSAZZ01 m s -1 derived from uship and vship

Following transfer the data were screened using BODC in-house visualisation software. Suspect data values were assigned the appropriate BODC data quality flag. Missing data values, where present, were changed to the missing data value and assigned a BODC data quality flag

Originator's Data Processing

Sampling strategy

The RDI broad band 150 kHz (Ocean Surveyor) phased array style vessel-mounted Acoustic Doppler Current Profiler (VM-ADCP) was operated and logged throughout the cruise.

The 150 kHz VM-ADCP is mounted in the hull at a depth of 5.3 m.

Originators Data Processing

The data were acquired using the VmDas software package version 1.42.

Field Calibrations

A calibration of both VM-ADCPs was achieved using bottom tracking performed at the beginning of the section on the Celtic Shelf from day 196-198. The calibrations were given as follows:

Initial Data Inspection

After the end of Station 28 (day 212, 15:45) the velocities have a large obvious bias in the direction of travel. This appears to be as a result of increased inclement weather conditions, with resulting bubble formation affecting the transmission of the pulse of the transducer.

Anomalous scattering (due to scattering layers such as zooplankton) has been observed using a 75kHz instrument on previous cruises (e.g. D346). However, a large consistent bias caused by anomalous scattering was not observed on this cruise, which may be because only a 150kHz instrument was used, which does not penetrate as far into the ocean as the 75kHz instrument.

There were several issues with the links to the navigation files, and the navigation source changing during data acquisition.


Project Information

The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) project document

The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) brings together scientists with interests in physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems, and other users and collectors of ocean interior data to develop a sustained global network of hydrographic sections as part of the Global Ocean / Climate Observing System.

The GO-SHIP Panel was established in 2007 by the IOCCP and CLIVAR to develop a strategy for a sustained global repeat hydrography program as a contribution to the OceanObs09 Conference (September 2009) and to revise the 1994 WOCE hydrographic program manual. Based on community discussions at the OceanObs09 Conference, the Panel recommended the development of a sustained repeat hydrography program to:

The IOCCP and CLIVAR International Project Offices have agreed to provide project office support to this program as it develops.

Project office support for GO-SHIP is provided by the IOC-SCOR International Ocean Carbon Coordination Project (IOCCP) and the Climate Variability and Predictability Project (CLIVAR). Major financial support for this project is provided by the U.S. National Science Foundation through a grant to UNESCO - IOC (OCE - 0715161) and a grant to the Scientific Committee on Oceanic Research (OCE - 0608600) for the IOCCP.

For more information please see the official project website at GO-SHIP


Data Activity or Cruise Information

Cruise

Cruise Name D368
Departure Date 2011-07-15
Arrival Date 2011-08-04
Principal Scientist(s)Brian A King (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