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Metadata Report for BODC Series Reference Number 444333


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
SeaTech transmissometer  transmissometers
Aanderaa RCM 7/8 Recording Current Meter  current meters
Instrument Mounting subsurface mooring
Originating Country Germany
Originator -
Originating Organization University of Kiel
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) OMEX I
 

Data Identifiers

Originator's Identifier OMX3B/M
BODC Series Reference 444333
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1994-01-08 07:39
End Time (yyyy-mm-dd hh:mm) 1994-09-14 19:33
Nominal Cycle Interval 3600.0 seconds
 

Spatial Co-ordinates

Latitude 49.09420 N ( 49° 5.7' N )
Longitude 13.41000 W ( 13° 24.6' W )
Positional Uncertainty 1.0 to 5.0 n.miles
Minimum Sensor or Sampling Depth 1490.0 m
Maximum Sensor or Sampling Depth 1490.0 m
Minimum Sensor or Sampling Height 2183.0 m
Maximum Sensor or Sampling Height 2183.0 m
Sea Floor Depth 3673.0 m
Sea Floor Depth Source -
Sensor or Sampling Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor or Sampling Depth Datum Sea floor reference - Depth measured as a height above sea floor but converted into a depth relative to the sea surface according to the same datum as used for sea floor depth (applicable to instrument depths not bathymetric depths)
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
CNDCPR011Siemens per metreElectrical conductivity of the water body by in-situ conductivity cell
LCDAEL011Degrees TrueDirection (towards) of water current (Eulerian measurement) in the water body by in-situ current meter and correction to true North
LCSAEL011Centimetres per secondSpeed of water current (Eulerian measurement) in the water body by in-situ current meter
PSALPR011DimensionlessPractical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPPR011Degrees CelsiusTemperature 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

Transmissometer malfunction. All data appear to be of the same value (0.4170).


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 Recording Current Meter Model 7/8

Manufacturer's specifications: recording unit height 49.5cm (RCM8 52.0cm), diameter 12.8cm, vane size 48.5x50.0cm. Meter is designed for depths down to 2000m (RCM8 6000m). It incorporates a spindle which is shackled to the mooring line. The meter is attached to the spindle through a gimbal mounting which permits a maximum 27° deviation of the spindle from the vertical, the meter still remaining horizontal.

Meter comprises :

  1. Paddle wheel rotor magnetically coupled to an electronic counter

  2. Vane, which aligns instrument with current flow, has a balance weight ensuring static balance and tail fins to ensure dynamic balance in flows up to 250cm/s.

  3. Magnetic compass (needle is clamped to potentiometer ring) - direction recorded with 0.35° resolution, 5° accuracy for speeds 5 to 100cm/s, 7.5° accuracy for remaining speeds within 2.5 to 200cm/s range.

  4. Quartz clock, accuracy better than 2 sec/day within temperature range 0 to 20°C.

  5. Thermistor (temperature sensor), standard range -2.46 to 21.48°C (max on high range 36.04°C), accuracy 0.05°C, resolution 0.1 per cent of range, 63 per cent response time 12sec.

  6. Inductive cell conductivity sensor (optional), range 0 to 70mmho/cm standard resolution 0.1 per cent of range.

  7. Silicon piezoresistive bridge, standard range 0 to 3000 psi (RCM8 to 9000 psi), resolution 0.1% of range.

  8. Self balancing potentiometer which converts the output from each sensor into a 10 bit binary number for storage on magnetic tape.

  9. Associated electronics.

A built-in clock triggers the instrument at preset intervals and up to six channels are sampled in sequence. Channel 1 is a fixed reference reading for control purposes and data identification. Channels 2, 3 and 4 represent measurement of temperature, conductivity and pressure. Channels 5 and 6 represent the VECTOR AVERAGED current speed and direction since the previous triggering of the instrument. The number of rotor revolutions and the direction is sampled every 12 seconds and broken into North and East components. Successive components are added and recorded as speed and direction. For recording intervals longer than 10 minutes, speed and direction are sampled 1/50th of recording interval.

It has become common practice in some laboratories to deploy these meters as temperature and conductivity loggers without current measuring capabilities.

The following link will provide the manufacturer specifications:

Manufacturer specifications

SeaTech Transmissometer

Introduction

The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.

Specifications

  • Water path length: 5 cm (for use in turbid waters) to 1 m (for use in clear ocean waters).
  • Beam diameter: 15 mm
  • Transmitted beam collimation: <3 milliradians
  • Receiver acceptance angle (in water): <18 milliradians
  • Light source wavelength: usually (but not exclusively) 660 nm (red light)

Notes

The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

Further details can be found in the manufacturer's Manual.

BODC Current Meter Screening

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

  • Irregularities such as unfeasible values
  • Inconsistencies between related information. For example:
    • Depths of meter and sea bed.
    • Times for mooring deployment and for start/end of data series.
    • Length of record or number of data cycles, the cycle interval, the clock error and the period over which accrued.
    • Parameters stated as measured and the parameters actually present in the data cycles.
  • Originator's comments on meter/mooring performance and data quality.

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non- oceanographic origin may be tagged with the BODC flag denoting suspect value.

The following types of irregularity, each relying on visual detection in the time series plot, are amongst those which may be flagged as suspect:

  • Spurious data at the start or end of the record.
  • Obvious spikes occurring in periods free from meteorological disturbance.
  • A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities, deemed abnormal, then instead of flagging the individual suspect values, a caution may be documented. Likewise documents will highlight irregularities seen in the current vector scatter plots such as incongruous centre holes, evidence of mooring 'knock-down', abnormal asymmetry in tidally dominated records or gaps as when a range of speeds or directions go unregistered due to meter malfunction.

The term 'knock-down' refers to the situation when the 'drag' exerted on a mooring at high current speeds may cause instruments to tilt beyond the angle at which they are intended to operate. At this point the efficiency of the current sensors to accurately record the flow is reduced.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought, and where necessary, documented. This covers inconsistencies in the following:

  • Maximum and minimum values of parameters (spikes excluded).
  • The orientation and symmetry of the current vector scatter plot.
  • The direction of rotation of the current vectors.
  • The approximate amplitude and periodicity of the tidal currents.
  • The occurrence of meteorological events and, finally, for series for which no time check was possible, the phase.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.


Project Information

Ocean Margin EXchange (OMEX) I

Introduction

OMEX was a European multidisciplinary oceanographic research project that studied and quantified the exchange processes of carbon and associated elements between the continental shelf of western Europe and the open Atlantic Ocean. The project ran in two phases known as OMEX I (1993-1996) and OMEX II - II (1997-2000), with a bridging phase OMEX II - I (1996-1997). The project was supported by the European Union under the second and third phases of its MArine Science and Technology Programme (MAST) through contracts MAS2-CT93-0069 and MAS3-CT97-0076. It was led by Professor Roland Wollast from Université Libre de Bruxelles, Belgium and involved more than 100 scientists from 10 European countries.

Scientific Objectives

The aim of the Ocean Margin EXchange (OMEX) project was to gain a better understanding of the physical, chemical and biological processes occurring at the ocean margins in order to quantify fluxes of energy and matter (carbon, nutrients and other trace elements) across this boundary. The research culminated in the development of quantitative budgets for the areas studied using an approach based on both field measurements and modeling.

OMEX I (1993-1996)

The first phase of OMEX was divided into sub-projects by discipline:

  • Physics
  • Biogeochemical Cycles
  • Biological Processes
  • Benthic Processes
  • Carbon Cycling and Biogases

This emphasises the multidisciplinary nature of the research.

The project fieldwork focussed on the region of the European Margin adjacent to the Goban Spur (off the coast of Brittany) and the shelf break off Tromsø, Norway. However, there was also data collected off the Iberian Margin and to the west of Ireland. In all a total of 57 research cruises (excluding 295 Continuous Plankton Recorder tows) were involved in the collection of OMEX I data.

Data Availability

Field data collected during OMEX I have been published by BODC as a CD-ROM product, entitled:

  • OMEX I Project Data Set (two discs)

Further descriptions of this product and order forms may be found on the BODC web site.

The data are also held in BODC's databases and subsets may be obtained by request from BODC.


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 1994-01-08
End Date (yyyy-mm-dd) 1994-09-14
Organization Undertaking ActivityUniversity of Kiel
Country of OrganizationGermany
Originator's Data Activity IdentifierOMEX3B
Platform Categorysubsurface mooring

OMEX Moored Instrument Rig OMEX3B

Site: OMEX3

Position 49.0942° N, 13.4100° W
Water depth 3673 m
Deployed 08 Jan 1994
from Meteor (M27_1)
Recovered 14 Sep 1994
from Meteor (M30_1)

Instruments deployed on the rig

Height above
Sea Bed
Instrument
3117 m Sediment trap
3093 m Aanderaa current meter (#11039)
2207 m Sediment trap
2183 m Aanderaa current meter (#11038) + transmissometer
417 m Sediment trap
393 m Aanderaa current meter (#11040) + transmissometer

Related Data Activity activities are detailed in Appendix 1

Cruise

Cruise Name M27_1
Departure Date 1993-12-29
Arrival Date 1994-01-17
Principal Scientist(s)Wolfgang Balzer (University of Bremen, Center for Marine Environmental Sciences)
Ship FS Meteor

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameOMEX I site OMEX3
CategoryOffshore area
Latitude49° 5.28' N
Longitude13° 23.40' W
Water depth below MSL3670.0 m

OMEX I Moored Instrument and CTD site OMEX3

OMEX3 was one of four fixed stations for the OMEX I project. It was visited by eleven cruises and collected a variety of data during the period June 1993 to October 1995. These include:

  • Mooring deployments - Aandeera current meters with transmissometers
  • CTD casts
  • Net trawls
  • Plankton recorders
  • Cores
  • Water samples

The data collected a site OMEX3 lay within a box bounded by co-ordinates 48° 56.9'N, 013° 42.69'W at the southwest corner and 49° 6.5'N, 013° 17.1'W at the northeast corner, with an approximate depth of 3650 metres.

Related Fixed Station activities are detailed in Appendix 2


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

Appendix 1: OMEX3B

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
444345Currents -subsurface Eulerian1994-01-08 07:34:0049.0942 N, 13.41 WFS Meteor M27_1
444357Currents -subsurface Eulerian1994-01-08 07:37:0049.0942 N, 13.41 WFS Meteor M27_1

Appendix 2: OMEX I site OMEX3

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
920613CTD or STD cast1993-06-26 06:08:0049.06933 N, 13.429 WFS Poseidon PO200_7
319408Currents -subsurface Eulerian1993-06-26 14:31:0049.0942 N, 13.4288 WFS Poseidon PO200_7
319433Currents -subsurface Eulerian1993-06-26 14:43:0049.0942 N, 13.4288 WFS Poseidon PO200_7
319421Currents -subsurface Eulerian1993-06-26 16:26:0049.0942 N, 13.4288 WFS Poseidon PO200_7
920268CTD or STD cast1993-06-30 01:23:0049.003 N, 13.497 WValdivia VLD137
920281CTD or STD cast1993-06-30 03:09:0049.015 N, 13.519 WValdivia VLD137
883871CTD or STD cast1993-09-26 06:12:0049.08983 N, 13.37367 WRV Belgica BG9322A
883883CTD or STD cast1993-09-26 09:08:0049.1185 N, 13.42367 WRV Belgica BG9322A
1271535Water sample data1993-09-26 09:52:0049.11844 N, 13.42365 WRV Belgica BG9322A
883895CTD or STD cast1993-09-26 15:28:0049.12883 N, 13.43617 WRV Belgica BG9322A
883902CTD or STD cast1993-09-26 18:36:0049.14583 N, 13.482 WRV Belgica BG9322A
1271560Water sample data1993-09-26 18:46:0049.14583 N, 13.48192 WRV Belgica BG9322A
914877CTD or STD cast1993-10-24 09:14:0049.08333 N, 13.43 WRV Pelagia PE093
908177CTD or STD cast1994-01-07 05:16:0049.07333 N, 13.415 WFS Meteor M27_1
908189CTD or STD cast1994-01-07 21:22:0049.05667 N, 13.40833 WFS Meteor M27_1
908190CTD or STD cast1994-01-08 04:17:0049.08167 N, 13.43 WFS Meteor M27_1
444345Currents -subsurface Eulerian1994-01-08 07:34:0049.0942 N, 13.41 WFS Meteor M27_1
444357Currents -subsurface Eulerian1994-01-08 07:37:0049.0942 N, 13.41 WFS Meteor M27_1
908208CTD or STD cast1994-01-08 08:00:0049.08 N, 13.435 WFS Meteor M27_1
887491CTD or STD cast1994-04-30 02:24:0049.0845 N, 13.30117 WRRS Charles Darwin CD85
887429CTD or STD cast1994-04-30 03:09:0049.08983 N, 13.3 WRRS Charles Darwin CD85
1663785Water sample data1994-05-29 08:37:0049.08648 N, 13.43338 WRRS Charles Darwin CD86
974008CTD or STD cast1994-05-29 09:51:0049.0865 N, 13.43333 WRRS Charles Darwin CD86
910342CTD or STD cast1994-09-14 18:58:0049.09083 N, 13.41133 WFS Meteor M30_1
442953Currents -subsurface Eulerian1994-09-15 09:30:0049.0883 N, 13.39 WFS Meteor M30_1
442977Currents -subsurface Eulerian1994-09-15 10:08:0049.0883 N, 13.39 WFS Meteor M30_1
442965Currents -subsurface Eulerian1994-09-15 14:35:0049.0883 N, 13.39 WFS Meteor M30_1
915021CTD or STD cast1995-08-23 06:10:0049.08317 N, 13.43067 WRV Pelagia PE95A
886463CTD or STD cast1995-09-30 05:45:0049.084 N, 13.4195 WRRS Discovery D217
1676267Water sample data1995-09-30 06:23:0049.08403 N, 13.41943 WRRS Discovery D217
886395CTD or STD cast1995-10-06 09:27:0049.091 N, 13.38417 WRRS Discovery D217
1676311Water sample data1995-10-06 11:18:0049.09093 N, 13.38417 WRRS Discovery D217
886402CTD or STD cast1995-10-06 14:00:0049.08067 N, 13.4025 WRRS Discovery D217
1676323Water sample data1995-10-06 14:15:0049.08059 N, 13.40249 WRRS Discovery D217
886414CTD or STD cast1995-10-07 05:01:0049.07717 N, 13.38917 WRRS Discovery D217
886426CTD or STD cast1995-10-07 08:07:0049.0835 N, 13.41383 WRRS Discovery D217