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Metadata Report for BODC Series Reference Number 444308


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 OMX2B/2/B
BODC Series Reference 444308
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1994-04-18 14:04
End Time (yyyy-mm-dd hh:mm) 1994-09-16 09:04
Nominal Cycle Interval 3600.0 seconds
 

Spatial Co-ordinates

Latitude 49.18650 N ( 49° 11.2' N )
Longitude 12.81940 W ( 12° 49.2' W )
Positional Uncertainty 1.0 to 5.0 n.miles
Minimum Sensor or Sampling Depth 1070.0 m
Maximum Sensor or Sampling Depth 1070.0 m
Minimum Sensor or Sampling Height 386.0 m
Maximum Sensor or Sampling Height 386.0 m
Sea Floor Depth 1456.0 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 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) 1994-04-18
End Date (yyyy-mm-dd) 1994-09-16
Organization Undertaking ActivityUniversity of Kiel
Country of OrganizationGermany
Originator's Data Activity IdentifierOMEX2B/2
Platform Categorysubsurface mooring

OMEX Moored Instrument Rig OMEXB/2

Site: OMEX2

Position 49.1865° N, 12.8194° W
Water depth 1456 m
Deployed 18 Apr 1994
from RRS Charles Darwin (CD85)
Recovered 16 Sep 1994
from Meteor (M30_1)

Instruments deployed on the rig

Height above
Sea Bed
Instrument
860 m Sediment trap
836 m Aanderaa current meter (#11075)
410 m Sediment trap
386 m Aanderaa current meter (#11041) + transmissometer

Related Data Activity activities are detailed in Appendix 1

Cruise

Cruise Name CD85
Departure Date 1994-04-11
Arrival Date 1994-05-07
Principal Scientist(s)Phil Pugh (Institute of Oceanographic Sciences Deacon Laboratory)
Ship RRS Charles Darwin

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameOMEX I site OMEX2
CategoryOffshore area
Latitude49° 11.46' N
Longitude12° 48.00' W
Water depth below MSL1418.0 m

OMEX I Moored Instrument and CTD site OMEX2

OMEX2 was one of four fixed stations for the OMEX I project. It was visited by twelve 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 OMEX2 lay within a box bounded by co-ordinates 49° 6.72'N, 013° 16.03'W at the southwest corner and 49° 17.2'N, 012° 44.4'W at the northeast corner, with an approximate depth of 1500 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: OMEX2B/2

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
444321Currents -subsurface Eulerian1994-04-18 13:56:0049.1865 N, 12.8194 WRRS Charles Darwin CD85

Appendix 2: OMEX I site OMEX2

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
444382Multiple data types -fixed platform1993-06-24 20:29:0049.1885 N, 12.7333 WFS Poseidon PO200_7
319390Currents -subsurface Eulerian1993-06-27 11:49:0049.2872 N, 12.8193 WFS Poseidon PO200_7
319389Currents -subsurface Eulerian1993-06-27 12:27:0049.2872 N, 12.8193 WFS Poseidon PO200_7
920244CTD or STD cast1993-06-29 14:29:0049.193 N, 12.944 WValdivia VLD137
920256CTD or STD cast1993-06-29 15:13:0049.179 N, 12.957 WValdivia VLD137
883705CTD or STD cast1993-09-25 07:41:0049.22783 N, 12.80017 WRV Belgica BG9322A
883717CTD or STD cast1993-09-25 12:36:0049.25967 N, 12.80733 WRV Belgica BG9322A
1271492Water sample data1993-09-25 12:53:0049.25973 N, 12.80741 WRV Belgica BG9322A
883729CTD or STD cast1993-09-25 15:46:0049.26067 N, 12.81033 WRV Belgica BG9322A
883730CTD or STD cast1993-09-25 17:22:0049.1975 N, 12.74367 WRV Belgica BG9322A
1271511Water sample data1993-09-25 17:57:0049.1975 N, 12.74369 WRV Belgica BG9322A
883742CTD or STD cast1993-09-25 19:55:0049.23033 N, 12.794 WRV Belgica BG9322A
1271523Water sample data1993-09-25 20:18:0049.23031 N, 12.79403 WRV Belgica BG9322A
914969CTD or STD cast1993-10-21 08:46:0049.18667 N, 12.81967 WRV Pelagia PE093
908153CTD or STD cast1994-01-05 13:06:0049.18333 N, 12.81 WFS Meteor M27_1
908165CTD or STD cast1994-01-05 16:47:0049.17 N, 12.79167 WFS Meteor M27_1
444369Currents -subsurface Eulerian1994-01-11 08:41:0049.1883 N, 12.795 WFS Meteor M27_1
444370Currents -subsurface Eulerian1994-01-11 08:55:0049.1883 N, 12.795 WFS Meteor M27_1
908233CTD or STD cast1994-01-11 17:01:0049.21167 N, 12.88333 WFS Meteor M27_1
887362CTD or STD cast1994-04-16 06:51:0049.4215 N, 12.7765 WRRS Charles Darwin CD85
887301CTD or STD cast1994-04-18 03:36:0049.1445 N, 12.7865 WRRS Charles Darwin CD85
887313CTD or STD cast1994-04-18 05:53:0049.16517 N, 12.768 WRRS Charles Darwin CD85
444321Currents -subsurface Eulerian1994-04-18 13:56:0049.1865 N, 12.8194 WRRS Charles Darwin CD85
887325CTD or STD cast1994-04-18 21:15:0049.133 N, 12.82217 WRRS Charles Darwin CD85
974033CTD or STD cast1994-05-25 13:50:0049.194 N, 12.745 WRRS Charles Darwin CD86
1663773Water sample data1994-05-25 14:24:0049.19405 N, 12.74502 WRRS Charles Darwin CD86
444394Multiple data types -fixed platform1994-06-30 22:15:0049.1873 N, 12.8218 WRRS Charles Darwin CD86
910378CTD or STD cast1994-09-16 02:37:0049.18333 N, 12.845 WFS Meteor M30_1
442941Currents -subsurface Eulerian1994-09-16 13:10:0049.1912 N, 12.8 WFS Meteor M30_1
442928Currents -subsurface Eulerian1994-09-16 13:14:0049.1912 N, 12.8 WFS Meteor M30_1
885275CTD or STD cast1995-06-12 23:00:0049.2025 N, 12.8185 WRRS Charles Darwin CD94
915008CTD or STD cast1995-08-21 06:15:0049.1865 N, 12.8195 WRV Pelagia PE95A
915162CTD or STD cast1995-09-18 19:37:0049.18983 N, 12.74183 WRV Pelagia PE95B
886475CTD or STD cast1995-10-01 04:24:0049.19567 N, 12.811 WRRS Discovery D217
886358CTD or STD cast1995-10-05 05:00:0049.1875 N, 12.80517 WRRS Discovery D217
886371CTD or STD cast1995-10-05 11:37:0049.191 N, 12.84267 WRRS Discovery D217
1676280Water sample data1995-10-05 12:39:0049.19099 N, 12.84267 WRRS Discovery D217
886383CTD or STD cast1995-10-05 14:53:0049.1955 N, 12.85833 WRRS Discovery D217
1676292Water sample data1995-10-05 15:07:0049.19553 N, 12.85834 WRRS Discovery D217
886229CTD or STD cast1995-10-14 05:20:0049.19217 N, 12.8065 WRRS Discovery D217
1676359Water sample data1995-10-14 05:35:0049.19215 N, 12.80656 WRRS Discovery D217