Metadata Report for BODC Series Reference Number 41110


Metadata Summary

Data Description

Data Category Offshore sea floor pressure series
Instrument Type
NameCategories
Institute of Oceanographic Sciences MkIII bottom pressure recorder  sea level recorders
Instrument Mounting fixed benthic node
Originating Country United Kingdom
Originator -
Originating Organization Institute of Oceanographic Sciences Bidston Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier D4MP1/PDFH4
BODC Series Reference 41110
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1975-01-27 16:37
End Time (yyyy-mm-dd hh:mm) 1975-03-11 13:08
Nominal Cycle Interval 900.0 seconds
 

Spatial Co-ordinates

Latitude 36.92160 N ( 36° 55.3' N )
Longitude 9.69990 W ( 9° 42.0' W )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor Depth 1983.0 m
Maximum Sensor Depth 1983.0 m
Minimum Sensor Height 0.0 m
Maximum Sensor Height 0.0 m
Sea Floor Depth 1983.0 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)
PPSSRL01 1 Decibars RelBotPress Pressure (measured variable) exerted by the water body by fixed in-situ pressure sensor and corrected using co-located air pressure data expressed to unspecified datum by subtraction of a constant
 

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

IOS Off-Shore Pressure Recorder Mark III

The main part of the capsule is a forged aluminium sphere of 0.66m internal diameter, which contains the data logging system, acoustic command and release units and all battery supplies. Each half of the sphere is bolted to a central equatorial ring, a seal being provided by O rings.

There are twelve outlets through this ring for Marsh Marine type electrical connectors. The sphere is housed in a free flooding tubular aluminium alloy frame. Also mounted on this frame are 2 pressure transducers, a sea temperature unit, 2 subsidary platinum resistance thermometers for measuring sea temperature and 2 wound nickel scrolls that act as acoustic pinger beacons. The frame and sphere, complete with attachments, have a positive buoyancy, and in order to anchor them, they are mounted on a steel tripod. The tripod is attached to the main frame by a central pyro-release unit.

The system incorporates a commercial data logger modified to operate in the deep sea capsule. The logger will accept input from a total of twelve separate sources or channels. The temperature and pressure sensors have variable frequency outputs. The frequencies are counted over a 890 second period and the total count for each channel is then recorded during a scan of all channels which lasts for 10 seconds. Thus the averaged integrated pressure and temperature values are logged every 15 minutes. Temperature is measured to correct for the temperature coefficient of the pressure transducers.

Data Processing Notes

Clock lost 52 seconds over 42 days 20 hours 30 minutes 52 seconds; the cycle interval and time values have been corrected.

Instrument Characteristics

Station D4

OSTG Mark III Number 7
Sensors SG 1D/2 (BODC Series Ref. 41110)
SG 1D/3 (BODC Series Ref. 41122)
Nominal sampling interval 900 seconds
Integration period 890 seconds

IOS Data Processing of Off-Shore Pressure Recorder Data

Data processing comprises 2 stages:-

  1. Instrumental drift and depth are removed, thus the drift free series is produced with an artificial mean of zero.

  2. Generally the pressure values have been obtained by integration and averaging over the sampling interval, followed by logging; hence the time value assigned to a data cycle has been chosen as the mid-point between the start and end time of each interval. Some pressure records have been sample rate reduced from the basic time step of the recorder to produce either hourly or 15 minute values, incorporating any timing corrections due to clock error.


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