Metadata Report for BODC Series Reference Number 477222


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type Acoustic doppler current profiler
Instrument Mounting fixed benthic node
Originating Country United Kingdom
Originator -
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Project(s) Land Ocean Interaction Study (LOIS)
LOIS Shelf Edge Study (LOIS - SES)
 

Data Identifiers

Originator's Identifier rd0394.782
BODC Series Reference 477222
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1996-07-14 15:27
End Time (yyyy-mm-dd hh:mm) 1996-07-25 08:47
Nominal Cycle Interval 300.0 seconds
 

Spatial Co-ordinates

Latitude 56.45500 N ( 56° 27.3' N )
Longitude 9.08180 W ( 9° 4.9' W )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor Depth 46.0 m
Maximum Sensor Depth 398.0 m
Minimum Sensor Height 14.0 m
Maximum Sensor Height 366.0 m
Sea Floor Depth 412.0 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 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
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)
LCEWAP01 2 Centimetres per second CurrVelE_ADCP Eastward current velocity (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP)
LCNSAP01 2 Centimetres per second CurrVelN_ADCP Northward current velocity (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP)
LERRAP01 2 Centimetres per second ADCPER Current velocity error in the water body by moored acoustic doppler current profiler (ADCP)
LRZAAP01 2 Centimetres per second ADCPVC Upward current velocity 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

The data set contained a number of spikes. In cases where these could be unambiguously identified they have been flagged suspect.

An increase in noise level was generally observed from bin 30 onwards (shallower than 150 m) for the vertical component and from bin 35 onwards (shallower than 126 m) for the NS and EW components. The noise levels were generally consistent throughout the record and no periods of exceptionally high or low noise could be identified.

For the shallowest bins 44 and 45 (54 m and 46 m) systematic editing proved impossible due to high noise level. Data from these two bins should be viewed with caution.


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

RDI Acoustic Doppler Current Profiler

Acoustic Doppler Current Profilers (ADCPs) use sound waves to determine vertical profiles of currents, and may be deployed fixed to the sea floor, attached to a surface buoy, mounted on the hull of a ship, towed behind a ship or lowered on a cable.

ADCPs transmit sound bursts into the water. Particles carried by the water currents scatter the sound back to the transducer. As echoes return from further ranges from the sensor, the instrument assigns different water depths to the returning signals. Motion of the scattering particles relative to the sound source causes a change in the frequency of the sound (known as Doppler shift). The ADCP measures this change to produce vertical profiles of water velocity at up to 128 depths throughout the water column.

Specifications:
number of depth cells 1 to 128;
size of depth cells 0.12 to 32.00 metres;
velocity range +/- 10 m/s.

General Data Screening carried out by BODC

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 or depth 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 data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as 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.


Project Information

Land Ocean Interaction Study (LOIS)

Introduction

The Land Ocean Interaction Study (LOIS) was a Community Research Project of the Natural Environment Research Council (NERC). The broad aim of LOIS was to gain an understanding of, and an ability to predict, the nature of environmental change in the coastal zone around the UK through an integrated study from the river catchments through to the shelf break.

LOIS was a collaborative, multidisciplinary study undertaken by scientists from NERC research laboratories and Higher Education institutions. The LOIS project was managed from NERC's Plymouth Marine Laboratory.

The project ran for six years from April 1992 until April 1998 with a further modelling and synthesis phase beginning in April 1998 and ending in April 2000.

Project Structure

LOIS consisted of the following components:

Marine Fieldwork

Marine field data were collected between September 1993 and September 1997 as part of RACS(C) and SES. The RACS data were collected throughout this period from the estuaries and coastal waters of the UK North Sea coast from Great Yarmouth to the Tweed. The SES data were collected between March 1995 and September 1996 from the Hebridean slope. Both the RACS and SES data sets incorporate a broad spectrum of measurements collected using moored instruments and research vessel surveys.


LOIS Shelf Edge Study (LOIS - SES)

Introduction

SES was a component of the NERC Land Ocean Interaction Study (LOIS) Community Research Programme that made intensive measurements from the shelf break in the region known as the Hebridean Slope from March 1995 to September 1996.

Scientific Rationale

SES was devoted to the study of interactions between the shelf seas and the open ocean. The specific objectives of the project were:

Fieldwork

The SES fieldwork was focussed on a box enclosing two sections across the shelf break at 56.4-56.5 °N and 56.6-56.7 °N. Moored instrument arrays were maintained throughout the experiment at stations with water depths ranging from 140 m to 1500 m, although there were heavy losses due to the intensive fishing activity in the area. The moorings included meteorological buoys, current meters, transmissometers, fluorometers, nutrient analysers (but these never returned any usable data), thermistor chains, colour sensors and sediment traps.

The moorings were serviced by research cruises at approximately three-monthly intervals. In addition to the mooring work this cruises undertook intensive CTD, water bottle and benthic surveys with cruise durations of up to 6 weeks (3 legs of approximately 2 weeks each).

Moored instrument activities associated with SES comprised current measurements in the North Channel in 1993 and the Tiree Passage from 1995-1996. These provided boundary conditions for SES modelling activities.

Additional data were provided through cruises undertaken by the Defence Evaluation and Research Agency (DERA) in a co-operative programme known as SESAME.


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 1996-07-14
End Date (yyyy-mm-dd) 1996-07-25
Organization Undertaking ActivityProudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPOLRIG#7782
Platform Categoryfixed benthic node

Proudman Oceanographic Laboratory Moored Instrument Rig #782

This rig was deployed as part of the LOIS Shelf-Edge Study at site S400

Rig position 56° 27.30' N 09° 04.91' W
Deployed 14 Jul 1996 15:18
from RRS Challenger (cruise CH128A)
Recovered 25 Jul 1996 09:42
from RRS Challenger (cruise CH128A)

Instruments deployed on the rig

Height above
Sea Bed
Instrument
0.5m RDI Acoustic Doppler Current Profiler (#394)

Cruise

Cruise Name CH128A
Departure Date 1996-07-10
Arrival Date 1996-07-26
Principal Scientist(s)John H Simpson (University of Wales, Bangor School of Ocean Sciences)
Ship RRS Challenger

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameLOIS(SES) S400
CategoryOffshore location
Latitude56° 27.17' N
Longitude9° 4.85' W
Water depth below MSL397.0 m

LOIS (SES) Mooring and CTD Site S400

Site S400 was a fixed station where moorings were deployed during the Land-Ocean Interaction Study (LOIS) Shelf Edge Study (SES). It was also one of fourteen CTD sites on repeat section S, across the Hebridean Slope, occupied by cruises between March 1995 and September 1996.

Instrument Deployment History

The following tables summarise the instruments deployed at this site for which data may be available.

1995

Mar Apr May Jun Jul Aug Sep Oct Nov Dec
CM             a      
ADCP           a a b b b

1996

Jan Feb Mar Apr May Jun Jul Aug
CM                
ADCP c c d d       e

Each different letter in the tables above corresponds to an individual instrument record.

Glossary

Note

  1. Transmissometers may have been fitted to some of the current meters.
  2. Only periods for which useful data were returned are shown.

Other Cruises linked to this Fixed Station (with the number of series) - CH121A (2) CH121C (1) CH123B (1) CH125A (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