Metadata Report for BODC Series Reference Number 702801


Metadata Summary

Data Description

Data Category Offshore sea floor pressure series
Instrument Type
NameCategories
Aanderaa WLR 7 Water Level Recorder  sea level recorders; water temperature sensor
Instrument Mounting fixed benthic node
Originating Country United Kingdom
Originator Ms Sarah Hughes
Originating Organization Fisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory)
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier 716/W
BODC Series Reference 702801
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-08-09 10:31
End Time (yyyy-mm-dd hh:mm) 2005-08-12 08:44
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Latitude 57.53350 N ( 57° 32.0' N )
Longitude 5.68950 W ( 5° 41.4' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 17.0 m
Maximum Sensor Depth 17.0 m
Minimum Sensor Height 0.0 m
Maximum Sensor Height 0.0 m
Sea Floor Depth 17.0 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)
PREXPS01 1 Decibars MeasPress_SL Pressure (measured variable) exerted by the water body by fixed in-situ pressure sensor and corrected to read zero at sea level
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


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 Water Level Recorder Model 7

The Water Level Recorder (WLR) model 7 is a self-contained, high precision instrument specifically designed for recording of ocean water levels through precise measurement of hydrostatic pressure. The WLR records pressure, temperature and conductivity (optional) at regular intervals, enabling precise variations in water level to be calculated. The pressure sensor consists of an oscillating quartz crystal which shifts frequency with the force applied to it. Temperature is measured by a Fenwall thermistor.

The data from the WLR7 are stored in a solid-state data storage unit (DSU) which can store up to 65,500 ten bit, PDC-4 coded words in a set of EEPROMS. Click the link for further details on the WLR7 .

Specifications

Pressure

Oscillator Frequency 36-40 kHz
Resolution 0.001% of range
Repeatability ± 0.01% of full scale
Integration 40 s
Ranges available 0 - 700 kPA (60 m) (standard)
0 - 3500 kPa (340 m) (standard)

Temperature

The thermistor is a Fenwall GB32JM19

Range -3 °C to +35 °C
Accuracy ± 0.1 °C
Resolution 0.04 °C
Response Time 30 s

Conductivity (optional)

Sensor Type Conductivity Cell 3094
Ranges 0 - 77 mmho cm -1 (standard)
0 - 42 mmho cm -1 (on request)
Accuracy ± 0.25 mmho cm -1
Resolution 0.1% of range

Further details can be found in the manufacturer's specification sheet .

BODC Processing

Data were received by BODC in ASCII format files. For each instrument there is a file containing pressure and temperature time series.

These series were reformatted to the internal QXF format using BODC transfer function 325. The following table shows how the variables within the file were mapped to the appropriate BODC parameter codes.

Original parameter name Original Units Description BODC Parameter Code BODC Units Comments
Time DD/MM/YYYY HH:MI date and time AADYAA01 + AAFDZZ01 day number and day fraction GMT Conversion by transfer
P decibars Pressure PREXPS01 decibars  
T °C Temperature TEMPPR01 °C  

The deck pressure had not been measured, or removed from the data series, prior to submission of data to BODC. We thus derived a pressure offset from the instrument deployment pressure (calculated from deployment depth and latitude) and the first reading of the pressure time series. All water level recorders were bottom-mounted so the instrument depth was simply the depth of the seabed measured by the ship's echosounder at the time of deployment. The offset was applied to the entire series following the form: P corr = P orig - offset where P corr is the corrected pressure and P orig the original pressure reading.

Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged 'M'. Flags from the originator marking suspect data were retained during transfer and flagged 'L'.

Originator's Data Processing

Sampling Strategy

The water level recorder deployed in Loch Torridon had a sampling frequency of 60 readings per hour. The instrument included a temperature sensor.

Data Processing

DAF applied the standard manufacturers' calibrations to all data, and produced ASCII files for submission to BODC. Data files were named according to the instrument code (716w) and contained pressure and temperature time series.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2005-08-09
End Date (yyyy-mm-dd) 2005-08-12
Organization Undertaking ActivityFisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory)
Country of OrganizationUnited Kingdom
Originator's Data Activity Identifier716w
Platform Categoryfixed benthic node

DAF bottom mounted water level recorder, Loch Torridon

The water level recorder (WLR) was located at 57° 32.01' N, 005° 41.37' W in a nominal water depth of 17 m.

The Department of Agriculture and Fisheries (DAF, now known as Marine Scotland Aberdeen Marine Laboratory) used a small boat to deploy the WLR on 09 August 2005. It was recovered on 12 August 2005, and instrumentation details are included in the following table.

Instrument type Serial Number Deployment start Deployment end Instrument depth (m) Comments
Aanderaa WLR 7 940 2005-08-09 2005-08-12 17  

Cruise

Cruise Name 2005 Loch Shieldaig
Departure Date 2005-08-08
Arrival Date 2005-08-12
Principal Scientist(s)
Ship Fram

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