Metadata Report for BODC Series Reference Number 962646


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Aanderaa RCM 7/8 Recording Current Meter  current meters
Instrument Mounting subsurface mooring
Originating Country France
Originator Dr Valerie Quiniou-Ramus
Originating Organization Total S.A.
Processing Status QC in progress
Project(s) SIMORC
 

Data Identifiers

Originator's Identifier LOURO_RCM(719M_BMSL)_CURR&TEMP
BODC Series Reference 962646
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-01-17 12:00
End Time (yyyy-mm-dd hh:mm) 2009-07-25 09:30
Nominal Cycle Interval 600.0 seconds
 

Spatial Co-ordinates

Latitude 7.50400 S ( 7° 30.2' S )
Longitude 11.23420 E ( 11° 14.1' E )
Positional Uncertainty 0.01 to 0.05 n.miles
Minimum Sensor Depth 719.0 m
Maximum Sensor Depth 719.0 m
Minimum Sensor Height 1102.0 m
Maximum Sensor Height 1102.0 m
Sea Floor Depth 1821.0 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 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 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
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
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

SIMORC Data Quality Report Total Angola Block 32, Louro long mooring

Narrative

This long mooring forms the observations made in Angola Block 32, Louro.

Data Quality Information

This data quality report refers only to the Aanderaa RCM7 and RCM8 current meters on this mooring. The acoustic Aanderaa SEAGUARD RCM was not affected. A significant data gap was observed from 08:50 on 21st April 2009 to 13:20 on 23rd April 2009. After this gap, the RCM7 and RCM8 current meters seemed to have been reset slightly in that zero current speeds were recorded as 1.1 cm/sec. Prior to the gap, these had been recorded as speeds of zero cm/sec. Periods in excess of 30 minutes where speeds remained stuck at 1.1 cm/sec were flagged suspect.


Data Access Policy

SIMORC data access conditions

The data collated and held at BODC on behalf of the SIMORC project are restricted. However, the data will be available to download from the Official SIMORC Website, as part of the project protocol. The data set will initially include data from the oil companies TOTAL, Shell and BP.


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

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:

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:

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:

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.

BODC Processing

Data were received by BODC in ASCII format files (Fugro format). They were reformatted to QXF format using BODC transfer function 400. The following table shows how the variables within the files were mapped to the appropriate BODC parameter codes:

Original parameter name Original Units Description BODC Parameter Code BODC Units Comments
Time DD-MON-YY hh:mm:ss Date and time (GMT) AADYAA01 + AAFDZZ01 Day number and day fraction (GMT)  
Curr_Speed m/s Speed LCSAEL01 cm/sec *100
Curr_Direction degrees True Direction LCDAEL01 degrees True  
Temp degrees Celsius Sea temperature TEMPPR01 degrees Celsius  
Salinity PSU Salinity PSALPR01 PSU  

Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO.


Project Information

System of Industry Metocean data for the Offshore and Research Communities (SIMORC)

The EU-funded SIMORC project is a collaborative effort between MARIS (Netherlands), BODC (UK), the International Association of Oil and Gas Producers (OGP) and IOC-IODE to provide a harmonised and quality controlled metocean data set from data collected by oil and gas producers, accessible through the SIMORC protocol.


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2009-01-17
End Date (yyyy-mm-dd) 2009-07-25
Organization Undertaking ActivityTotal S.A.
Country of OrganizationFrance
Originator's Data Activity IdentifierLouro
Platform Categorysubsurface mooring

SIMORC Total Louro Current Meter and ADCP mooring.

The survey at this site was made up of a single mooring.

This long mooring was deployed in a water depth of 1832 metres. (Nominal position of 7.504°S 11.2342°E):

Meter No. Instrument Depth (m) Instrument Type Total Time Period Comments
9771 41.2 RDI 300kHz ADCP 16-JAN-2009 TO 26-JUL-2009 Upward-looking.
677 42.7 SeaBird SBE37 16-JAN-2009 TO 26-JUL-2009  
11520 446.1 RDI 75kHz ADCP 16-JAN-2009 TO 26-JUL-2009 Upward-looking.
288 446.1 SeaBird SBE39 16-JAN-2009 TO 26-JUL-2009  
12497 696.2 RCM7 16-JAN-2009 TO 26-JUL-2009  
11534 946.2 RCM8 16-JAN-2009 TO 26-JUL-2009  
12474 1196.2 RCM8 16-JAN-2009 TO 26-JUL-2009  
10050 1446.2 RCM8 16-JAN-2009 TO 26-JUL-2009  
11260 1696.2 RCM8 16-JAN-2009 TO 26-JUL-2009  
102 1822 Aanderaa Seaguard 16-JAN-2009 TO 26-JUL-2009 with Aanderaa WLR8

Other Series linked to this Data Activity - 962622 962634 962610 962671 963397 962449 962658 1052455 963385 962450

Cruise

Cruise Name Seabulk Luanda 2009
Departure Date 2009-01-14
Arrival Date 2009-01-19
Principal Scientist(s)
Ship Seabulk Luanda

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameLouro, Angola Block 32
CategoryOffshore location
Latitude7° 30.24' S
Longitude11° 14.05' E
Water depth below MSL1832.0 m

Total - Angola Block 32 - Louro

Latitude Longitude Water depth (m)
7.504°S 11.23417°E 1829

This fixed station is in Block 32, offshore Angola. A mooring was deployed at this site in January 2009 to cover a 12-month period of measurements of currents through the water column. Prior to the mooring deployment, a CTD dip was undertaken to check the actual water depth.

Other Series linked to this Fixed Station for this cruise - 962449 962450 962610 962622 962634 962658 962671 963385 963397 963428 963441

Other Cruises linked to this Fixed Station (with the number of series) - Petrogas1 (1)


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