Metadata Report for BODC Series Reference Number 897092


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Aanderaa doppler current sensor 4100  current meters
Instrument Mounting moored surface buoy
Originating Country United Kingdom
Originator Ms Sarah Hughes
Originating Organization Fisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory)
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier 726/1
BODC Series Reference 897092
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2006-07-11 15:40
End Time (yyyy-mm-dd hh:mm) 2006-11-16 10:00
Nominal Cycle Interval 600.0 seconds
 

Spatial Co-ordinates

Latitude 57.54650 N ( 57° 32.8' N )
Longitude 5.68717 W ( 5° 41.2' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 1.0 m
Minimum Sensor Height 139.0 m
Maximum Sensor Height 139.0 m
Sea Floor Depth 140.0 m
Sensor Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
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)
LCDAEL01 1 Degrees True CurrDir Current direction (Eulerian) in the water body by in-situ current meter and correction to true North
LCSAEL01 1 Centimetres per second CurrSpd_CM Current speed (Eulerian) in the water body by in-situ current meter
PSALPR01 1 Dimensionless P_sal Practical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPPR01 1 Degrees Celsius Temp Temperature of the water body
 

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

A scatter plot of the current data reveals an unusual distribution of points, which is roughly triangular in shape. This instrument is located at 1 m depth in a sea loch, so would be strongly influenced by wind-driven currents, and such effects may account for the observations.

Salinity data are noisy and highly variable at times. However, given that the environment in which the instrument was deployed would have been subject to fresh water influx, such noise is not unexpected and no data points have been flagged as suspect.


Data Access Policy

Public domain 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.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."


Narrative Documents

Aanderaa Doppler current sensors 4100, 4100R, 4100A and 4100RA

The Aanderaa 4100 current sensor is a rugged, true vector averaging sensor designed to measure current speed and direction in the ocean. Four transducers transmit short pulses (pings) of acoustic energy along narrow beams and receive the backscattered signals from particles in the water. The Doppler shift of the backscattered signal, coupled with data from the internal compass, allows the instrument to determine the current speed and direction. Current measurements are compensated for tilt by the use of an electrolytic tilt sensor whose accuracy is proportional to the square root of the number of pings in a measuring interval. Temperature is measured using a temperature dependent crystal-oscillator-circuit.

Three additional models are available: 4100R, 4100A and 4100RA. These operate in the same manner as the standard 4100, but there are some differences in specifications, as detailed below:

Other specifications are common to all models.

Specifications

Acoustic frequency 2 MHz
Beam angle ± 1° (main lobe)
Depth capability 300 m
Operating temperature -10 to 50°C
Ping rate

4100: 10 pings s -1 in intervals of 2 min or less; 1 ping s -1 in intervals > 2 min

4100R: selectable from 4 to 1200 pings per minute

Current Speed
Range

4100 and 4100R: 0 to 300 cm s -1

4100A and 4100RA: 0 to 500 cm s -1

Resolution 0.1 % full scale
Accuracy ± 0.15 cm s -1

± 1 % of reading

Standard deviation 0.55 cm s -1
Current Direction
Range 0 to 360° magnetic
Resolution 0.35°
Accuracy

± 5° for 0 to 15° tilt

± 7.5° for 15 to 35° tilt

Temperature
Range -10 to 43°C
Resolution 0.05°C
Accuracy ± 0.08°C
Tilt circuit
Accuracy ± 1.5°
Compass circuit
Accuracy ± 3°
Sensitivity 0.01 ppb
Typical range 0.01 to 230 ppb

Further details can be found in the manufacturer's specification sheet .

BODC Processing

Data were received by BODC in ASCII format files. This series was reformatted to the internal QXF format using BODC transfer function 325. The following table shows how the variables within the file were mapped to the appropriate BODC parameter codes.

Original parameter name Original Units Description BODC Parameter Code BODC Units Comments
Time DD/MM/YYYY HH:MI date and time AADYAA01 and AAFDZZ01 day number and day fraction GMT Conversion by transfer
u + v cm/s Eastward and northward current velocity LCDAEL01 (direction) and LCSAEL01 (speed) °, cm/s Converted by transfer to current direction (Eulerian) in the water column by in-situ current meter and correction to true North, and current speed (Eulerian) in the water column by in-situ current meter
T degrees Celsius Temperature TEMPPR01 degrees Celsius  
S dimensionless Salinity PSALPR01 dimensionless  

Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged 'M'. Flags from the originator marking suspect data were retained during transfer and flagged 'L'.

Originator's Data Processing

Sampling Strategy

The Aanderaa Doppler Current Sensor deployed in Loch Shieldaig had a sampling frequency of 6 readings per hour. The instrument included temperature and conductivity sensors.

Data Processing

FRS applied the standard manufacturers' calibrations to all current, temperature and salinity data, and produced ASCII files for submission to BODC. Data files were named according to the mooring code (726) and the instrument number (1). The current meter file (7261) contained eastward and northward velocities, and temperature. Corresponding salinity data were provided in a separate file (append s).


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2006-07-11
End Date (yyyy-mm-dd) 2006-11-16
Organization Undertaking ActivityFisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory)
Country of OrganizationUnited Kingdom
Originator's Data Activity Identifier726
Platform Categorymoored surface buoy

FRS current meter mooring, Loch Shieldaig

The mooring was located at 57° 32.79' N, 005° 41.23' W in a nominal water depth of 140 m.

The mooring was deployed on 11 July 2006 by Fisheries Research Services (FRS, now known as Marine Scotland Aberdeen Marine Laboratory) on cruise Fram 1206H (10 July 2006-14 July 2006), recovered on 16 November 2006, and consisted of the following instruments.

Instrument type Serial Number Deployment start Deployment end Instrument depth (m) Comments
Aanderaa Doppler Current Sensor 89 2006-07-11 2006-11-16 1  

Cruise

Cruise Name 1206H
Departure Date 2006-07-10
Arrival Date 2006-07-14
Principal Scientist(s)John Beaton (Fisheries Research Services Aberdeen Marine Laboratory)
Ship Fram

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