Metadata Report for BODC Series Reference Number 1102030

Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags

Metadata Summary

Data Description

Data Category

Currents -subsurface Eulerian

Instrument Type

Name	Categories
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

Online delivery of data

Download not available

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 or Sampling Depth	17.23 m
Maximum Sensor or Sampling Depth	489.3 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	Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum	-

Parameters

BODC CODE	Rank	Units	Title
BINNUMBR	0	Dimensionless	Bin number
AADYAA01	1	Days	Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01	1	Days	Time (time between 00:00 UT and timestamp)
ACYCAA01	1	Dimensionless	Sequence number
ALATGP01	1	Degrees	Latitude north relative to WGS84 by unspecified GPS system
ALONGP01	1	Degrees	Longitude east relative to WGS84 by unspecified GPS system
APEWAS01	1	Centimetres per second	Eastward velocity of measurement platform relative to ground surface by Ashtech GPS
APNSAS01	1	Centimetres per second	Northward velocity of measurement platform relative to ground surface by Ashtech GPS
APSAZZ01	1	Metres per second	Speed of measurement platform relative to ground surface {speed over ground}
DBINAA01	2	Metres	Depth (spatial coordinate) of ADCP bin relative to water surface {bin depth} in the water body
LCEWAS01	2	Centimetres per second	Eastward velocity of water current (Eulerian measurement) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCNSAS01	2	Centimetres per second	Northward velocity of water current (Eulerian measurement) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCSAAS01	2	Centimetres per second	Speed 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 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:

develop formal international agreements for a sustained international repeat ship-based hydrography program, including an internationally-agreed strategy and implementation plan building on the guidelines in the Community White Paper,
advocate for national contributions to this strategy and participation in the global program,
provide a central forum for communication and coordination, and
develop syntheses of hydrographic data, in partnership with national, regional, and global research programs.

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