Metadata Report for BODC Series Reference Number 1362810


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Nortek Aquadopp 6000 3D Doppler current meter  current meters; water temperature sensor
Instrument Mounting subsurface mooring
Originating Country United Kingdom
Originator Mr Povl Abrahamsen
Originating Organization British Antarctic Survey
Processing Status banked
Project(s) BAS Long Term Monitoring and Survey
 

Data Identifiers

Originator's Identifier OP3_1113_4_AQD_6000_1450M
BODC Series Reference 1362810
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2011-03-25 22:00
End Time (yyyy-mm-dd hh:mm) 2013-03-31 10:45
Nominal Cycle Interval 900.0 seconds
 

Spatial Co-ordinates

Latitude 60.65515 S ( 60° 39.3' S )
Longitude 42.22827 W ( 42° 13.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 1450.0 m
Maximum Sensor Depth 1450.0 m
Minimum Sensor Height 302.0 m
Maximum Sensor Height 302.0 m
Sea Floor Depth 1752.0 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)
ACYCAA01 1 Dimensionless Record_No Sequence number
HEADCM01 1 Degrees Platform_Heading Orientation (horizontal relative to true north) of measurement device {heading}
LCDAZZ01 1 Degrees True UnspCurrDir Current direction in the water body
LCEWZZ01 1 Centimetres per second CurrVelE Eastward current velocity in the water body
LCNSZZ01 1 Centimetres per second CurrVelN Northward current velocity in the water body
LCSAZZ01 1 Centimetres per second UnspCurrSpd Current speed (Eulerian) in the water body
LRZAZZZZ 1 Centimetres per second VertCurr Upward current velocity in the water body
PREXPR01 1 Decibars MeasPress_MW Pressure (measured variable) exerted by the water body by semi-fixed in-situ pressure sensor and corrected to read zero at sea level
PTCHFG01 1 Degrees Pitch_(Fluxgate) Orientation (pitch) of measurement platform by triaxial fluxgate compass
ROLLFG01 1 Degrees Roll_(Fluxgate) Orientation (roll angle) of measurement platform by triaxial fluxgate compass
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 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

Nortek Aquadopp Open Water Current Meter

This instrument provides 3D acoustic doppler current measurements along with standard measurements of temperature, pressure, tilt and direction. It can be used in real time measurement situations or can log to an internal recorder powered by internal batteries. It can also be configured to measure surface wave height, period and direction concurrently. It has the unique feature of being run in 'diagnostic' mode when set to collect data at 1 Hz frequency in user specified intervals. This allows studies of mooring motion and the performance of other current meters to be conducted. It can be set in various configurations with titanium housings for deployment at greater depths.

Standard Measured Parameters

Surface wave monitoring

The standard Aquadopp is suitable for measuring surface wave height, period, and direction, which are calculated using the PUV method whereby spectra are estimated based on a combination of the pressure signal recorded by the instrument (P) and two horizontal components of the wave orbital velocity (U and V). More specifically, the pressure signal is used to provide an estimate of the wave frequency spectrum. The energy in this spectrum is then used to estimate wave height and period. The measurements of the wave orbital velocities are used to provide an estimate of the wave direction. Since these estimates are based on the distribution of wave energy and are not direct measurements of the free surface, they should be considered inferred estimates.

Both the dynamic pressure and the orbital velocities are driven by surface waves. The signals that are associated with these properties are complicated by the fact that they attenuate (that is the signals are weaker) with depth. The exact behaviour of the attenuation is determined by the water depth and the wavelength being observed. The greater the water depth the greater the attenuation; likewise, the shorter the wavelength (or higher the frequency of the wave) the greater the attenuation for a given water depth. This means that the estimation of wave parameters is limited by both water depth and wave frequency.

Specifications

Water Velocity Measurement
Range ± 5 m/s (standard 300 m version)
± 3 m/s (3000 m and 6000 m versions - higher ranges available on request)
Accuracy 1% of measured value ± 0.5 cm/s
Max. sampling rate 1 Hz, 4 Hz also available on request (standard version)
Internal sampling rate 23 Hz
Measurement Area
Measurement cell size 0.75 m
Measurement cell position 0.35 - 5.0 m
Default position 0.35 - 1.8 m
Doppler uncertainty (noise)
Typical 0.5 - 1.0 cm/s
At 1 Hz sampling rate 1.5 cm/s
Echo Intensity
Acoustic frequency 2 MHz
Resolution 0.45 dB
Dynamic range 90 dB
Sensors
Temperature Thermistor embedded in head
Range -4°C to 40°C
Accuracy/resolution 0.1°C / 0.01°C
Time response 10 min
Compass Magnetometer
Accuracy/Resolution 2° / 0.1° for tilt < 20°
Tilt Liquid level
Maximum tilt 30°
Up or down Automatic detect
Pressure Piezoresistive
Range 0 - 300 m (standard), 0 - 3000 m or 0 - 6000 m
Accuracy/resolution 0.5%
Analogue Inputs
No. of channels 2
Voltage supply 12 V
Voltage input 16 bit A/D
Materials
Standard version Delrin with titanium screws
3000 m version Delrin with titanium screws
6000 m version Titanium with Delrin transducer head
Environmental
Operating temperature -4°C to 40°C
Dimensions
Cylinder 568 mm x 75 mm (standard)
619 mm x 84 mm (3000 m version)
625 mm x 84 mm (6000 m version)
Weight in air 3.5 kg (standard)
3.6 kg (3000 m version)
7.6 kg (6000 m version)
Weight in water Neutral (standard)
1.2 kg (3000 m version)
4.8 kg (6000 m version)

Further details can be found in the manufacturer's specification sheets for the Aquadopp , Aquadopp 3000 and Aquadopp 6000 .

BODC Processing

Data processing

The data arrived at BODC as individual .mat files containing data collected on moorings OP1, OP2, OP3, OP4, OP5, OP6, CI1 and CI2. They were submitted as part of an accession including 5 different types of instruments - Aquadopp, RCM8, RCM11, SBE37 and SBE39.

Reformatting

The parameters from the originator's files were reformatted to internal format using BODC standard procedures.

The following parameters from the Aquadopp data were not reformatted as they are considered metadata or are not environmental variables: date, depth (m), botdepth (m), lat/lon, mooringname, nomdepth (m), serial_no, type, temp_offset_applied and press_offset_applied.

The table below includes the final variables and how they were mapped to the appropriate BODC parameter codes:

Originator's Variable Originator's Units Description BODC Parameter Code BODC Units
dir deg Current direction in the water body LCDAZZ01 deg
heading deg Orientation (horizontal relative to true north) of measurement platform {heading} by compass HEADCM01 deg
pitch deg Orientation (pitch) of measurement platform by triaxial fluxgate compass PTCHFG01 deg
pressure dbar Pressure (measured variable) exerted by the water body by semi-fixed in-situ pressure sensor and corrected to read zero at sea level PREXPR01 dbar
roll deg Orientation (roll angle) of measurement platform by triaxial fluxgate compass ROLLFG01 deg
speed cm s -1 Current speed (Eulerian) in the water body LCSAZZ01 cm s -1
temp °C Temperature of the water body TEMPPR01 °C
u cm s -1 Eastward current velocity in the water body LCEWZZ01 cm s -1
v cm s -1 Northward current velocity in the water body LCNSZZ01 cm s -1
w cm s -1 Upward current velocity in the water body LRZAZZZZ cm s -1

Battery voltage and amplitude channels were reformatted to help with the screening process and are not included in the final file but are avaiable upon request.

None of the parameters required a unit conversion and no derived parameters were created during reformatting.

Screening

The reformatted data were visualised using in house software and spikes or improbable values were flagged accordingly.

Originator's Data Processing

Sampling Strategy

Sampling was carried out as part of the BAS LTMS (British Antarctic Survey Long Term Monitoring and Survey). The project involved the deployment of moorings CI1, CI2, OP1, OP2, OP3, OP4, OP5 and OP6 in the Southern Ocean, situated north of Coronation Island and the Orkney Passage in the Weddell and Scotia Sea.

Moorings OP1, OP2, OP3, OP4 and OP6 were first deployed in 2011, fitted with Nortek Aquadopp Deep Water current meters, and data have been collected at 15-minute intervals since then. Gaps in the series may be related to either instruments not being recovered, or data not being collected due to instrument malfunction.

Data Processing

Little information is known with regards to the exact details of the calibrations carried out on the mooring data. Originator's data processing, visualisation and calibration were done through the use of Matlab scripts written for Matlab R2014b version.

The originator did not apply corrections to current velocity, direction or components for magnetic variation as the variation in this region is less than one degree. According to the originator, it has been found that in some conditions Aquadopp current meters overread current speeds compared with a mechanical vector measuring current meter and there is considerable uncertainty associated with the exact corrections that should be applied. Because of the continuing uncertainties of how best to correct for the differing characteristics of these instruments, no correction has been applied to these data.

Offsets applied to the data were:

Serial Number Depth (m) Offset Applied
OP1 2011-03-26 — 2014-04-01  
6198 3607 -21 (temp), -0.02 (press)
6236 2944 -64 (temp), 0.0349 (press)
6180 2170 -8 (temp), 0.0501 (press)
5993 1826 -13 (temp), -0.0178 (press)
OP2 2011-03-27 — 2013-03-31  
6112 3062 -12 (temp), 0.02 (press)
6263 1700 -12 (temp), 0.02 (press)
OP3 2011-03-25 — 2013-03-31  
6251 1705 -12 (temp), 0.08 (press)
OP4 2011-03-27 — 2013-04-03  
6226 1844 -23 (temp), 0.016 (press)
OP6 2012-04-02 — 2013-03-30  
9264 2259 -22 (temp), 0.035 (press)
9250 2009 -22 (temp), 0.07 (press)

Project Information

BAS Long Term Monitoring and Survey

Introduction

The Long Term Monitoring and Survey project (LTMS) has been running since the British Antarctic Survey (BAS) was created. This project is one of the BAS core projects, with several groups of scientists collecting various types of data e.g biological, geological, atmospheric, among others.

Data collection is achievable through a wide scope of instruments and platforms, e.g. the Antarctic research stations, autonomous instrument platforms deployed on or from BAS research ships, BAS aircrafts, satellite remote sensing and others.

Scientific Objectives

This project was implemented in order to measure change and variability in the Earth system. Its long term duration allows for the monitoring of processes that could be missed in shorter term studies and experiments. The data collected is also used to check and improve the reliability of models used to stimulate and predict the behavior of the Earth system.

The main objectives are:

Data Availability

The data sets obtained through this project are available to the academic community.


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2011-03-25
End Date (yyyy-mm-dd) 2013-03-31
Organization Undertaking ActivityBritish Antarctic Survey
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierOP3
Platform Categorysubsurface mooring

Orkney Passage mooring 3 (OP3)

The mooring was deployed at the following positions:

Organisation Undertaking Activity British Antarctic Survey, Cambridge
Country of Organisation United Kingdom
Originator's Data Activity Identifier OP3
Platform Category Subsurface mooring
Latitude (+ve N) -60.6552
Longitude (+ve E) -42.2283
Water Depth (m) 1766

The mooring was deployed on the Orkney Passage on cruise JR20110319 (JR252, JR254C) on 25 March 2011 and recovery was done on cruise JR20130317 (JR272B, JR273A, JR281, UKD-4) on 31 March 2013.

The table below lists the instruments deployed on this mooring:

Instrument type Serial Number Data start (UT) Data end (UT) Instrument depth (m)
Sea Bird SBE39 1311 2011-03-25 22:00:00 2013-03-31 11:00:00 1244
Aquadopp 6000 2011-03-25 22:00:00 2013-03-31 10:45:01 1450
Sea Bird SBE37 2707 2011-03-25 22:00:01 2013-03-31 11:00:01 1450
Aquadopp 6251 2011-03-25 22:00:00 2013-03-31 10:44:59 1705
Sea Bird SBE37 7384 2011-03-25 22:00:01 2013-03-31 10:45:01 1733

Other Series linked to this Data Activity - 1223441 1223465 1223453 1362809

Cruise

Cruise Name JR20110319 (JR252, JR254C)
Departure Date 2011-03-19
Arrival Date 2011-04-06
Principal Scientist(s)Povl Abrahamsen (British Antarctic Survey)
Ship RRS James Clark Ross

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameOrkney Passage OP3
CategoryOffshore location
Latitude60° 39.86' S
Longitude42° 11.60' W
Water depth below MSL2000.0 m

Orkney Passage OP3 site

Site OP3 is part of the Orkney Passage mooring array which is an activity covered by the Long Term Monitoring and Survey British Antarctic Survey's (BAS) programme. The data collection is the result of an ongoing collaboration between BAS and the Lamont-Doherty Earth Observatory (LDEO).

This site has been occupied since 2007 but throughout the years it has been moved. The recovery/deployment history, including position details, is presented below:

Deployed Recovered
Year Cruise Year Cruise Latitude (+veN) Longitude (+ve E) Water Depth (m)
2007 ES20070116 (ES031, ES038, ES048) 2009 ES033b -60.6643 -42.1933 2000
2009 ES033b 2011 JR20110319 (JR252, JR254C) -60.6653 -42.1967 1952
2011 JR20110319 (JR252, JR254C) 2013 JR20130317 (JR272B, JR273A, JR281, UKD-4) -60.6552 -42.2283 1766
2013 JR20130317 (JR272B, JR273A, JR281, UKD-4) 2015 JR20150309 (JR272D, JR310) -60.6553 -42.2296 1752
2015 JR20150309 (JR272D, JR310)     -60.6554 -42.2300 1750

Detailed information for each deployment can be accessed from the OP3 Data Activity document.

Other Series linked to this Fixed Station for this cruise - 1223441 1223453 1223465 1362809

Other Cruises linked to this Fixed Station (with the number of series) - ES033a (4) ES20070116 (ES031, ES038, ES048) (4)


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