Metadata Report for BODC Series Reference Number 962425


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type Acoustic doppler current profiler
Instrument Mounting research vessel
Originating Country Netherlands
Originator Mr Chris Shaw
Originating Organization Shell International Exploration and Production BV
Processing Status QC in progress
Project(s) SIMORC
 

Data Identifiers

Originator's Identifier 5716_CURR
BODC Series Reference 962425
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1991-08-01 13:36
End Time (yyyy-mm-dd hh:mm) 1991-09-15 23:58
Nominal Cycle Interval 300.0 seconds
 

Spatial Co-ordinates

Start Latitude 6.32862 N ( 6° 19.7' N )
End Latitude 4.65730 N ( 4° 39.4' N )
Start Longitude 3.39833 E ( 3° 23.9' E )
End Longitude 1.90410 E ( 1° 54.2' E )
Positional Uncertainty 0.01 to 0.05 n.miles
Minimum Sensor Depth 8.0 m
Maximum Sensor Depth 456.0 m
Minimum Sensor Height -431.0 m
Maximum Sensor Height 17.0 m
Sea Floor Depth 25.0 m
Sensor Distribution Sensor fixed, measurements made at fixed depths - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)
Sensor Depth Datum Mean sea level - Depth expressed relative to mean sea level as defined by the data originator
Sea Floor Depth Datum Chart reference - Depth extracted from available chart
 

Parameters

BODC CODE Rank Units Short Title Title
DBINAA01 0 Metres BinDep Depth below sea surface (ADCP bin)
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
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
LCDAAP01 2 Degrees True CurrDir_ADCP Current direction (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP) and correction to true North
LCSAAP01 2 Centimetres per second CurrSpd_ADCP Current speed (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP)
 

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 Shell Nigeria Vessel-mounted ADCP data narrative

Narrative

Data Quality Information

The ADCP data was not flagged. However, significant gaps in the data were recorded as follows:

Additionally, many of the deeper bins were null for the majority of the entire timeseries for direction and to a lesser extent, speed.


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

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 an ASCII format file (Metocean 3 format). This was reformatted to QXF format using BODC transfer function 370. 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 AADYAA01 + AAFDZZ01 Day number and day fraction Time zone assumed to be GMT.
Mean_total_Current_Speed m/s Speed LCSAAP01 cm/sec *100
Mean_total_Current_Direction degrees True Direction LCDAAP01 degrees True  
Scratch_parameter_2 decimal degrees North Latitude ALATGP01 decimal degrees North Values from all depth bins were identical, so only the surface bin values was used.
Scratch_parameter_3 decimal degrees East Longitude ALONGP01 decimal degrees North Values from all depth bins were identical, so only the surface bin values was used.

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

Cruise

Cruise Name 91-G-5
Departure Date 1991-08-01
Arrival Date 1991-09-15
Principal Scientist(s)
Ship Unknown research vessel

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