Metadata Report for BODC Series Reference Number 844859
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
Metadata Summary
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Problem Reports
No Problem Report Found in the Database
Data quality report: POLRIG994 ADV data
Data recorded by all three ADVs at the start of the deployment, from 06:00 UTC to 14:00 UTC 13 March 2007, were flagged. These first records were all taken after the instruments were activated but before the mooring deployment commenced.
Anomalously high standard deviation values were visible in the heading, pitch, roll, temperature and pressure channels in all three ADV datasets at 01:00 UTC 21 March 2007. This suggests that the mini-STABLE frame may have suffered a temporary knockdown at this time. No other data appear to be affected.
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
Acoustic Doppler Velocimeters (ADVs)
The ADV is a single-point, high resolution current meter, capable of recording three-dimensional velocity vectors. The ADV measures the velocity of the water by analysing the Doppler effect (frequency shift) of sound emitted by the sensor. The ADV uses a separate receiver and transmitter, both of which are constructed to generate very narrow beam patterns - the transmitter generates sound with most of the energy focussed in a narrow cone and the receiver is sensitive to sound reflected from a narrow angular range. The transducers are mounted so that their beams intersect at a volume of water located at some distance away from the sensor. Where the beams intersect is the volume of water in which the measurements are made - known as the sampling volume.
The transmitter generates a short pulse of sound at a known frequency, which travels through the water along the axis of the transmitter. As the sound beam passes through the sampling volume the its energy is scattered in all directions by suspended particulate matter (e.g. sediment, micro-organisms, bubbles). An ADV typically requires a concentration of >~10 mg/l scattering material for its operation. A small portion of the sound energy is scattered back along the receiver's axis and is sampled by the ADV, then processed to measure the change in frequency. The Doppler shift measured by one receiver is proportional to the velocity of the scattering particles along the axis of the transmitter and the receiver.
The typical noise level of the ADV is ~1% of the maximum recorded value during a deployment. For example, if the maximum recorded velocity during a deployment was 1 m/s, the noise level would be around 0.01 m/s.
Originator's Data Processing: ADV data from POLRIG994
Sampling Strategy
Three Sontek Ocean/Hydra Acoustic Doppler Velocimeters (ADVs) were attached to Proudman Oceanographic Laboratory (POL) mini-STABLE benthic frame POLRIG994 for deployment on PD04_07. Prior to deployment all three ADVs were bench tested at POL to check their operation. The ADVs all triggered on receipt of a sync pulse from the mini-STABLE SyncGen3 central timing clock. New battery packs were fitted prior to deployment and all o-rings plus sealing faces cleaned, checked for damage and then re-greased using Dow Corning silicon grease. SyncGen3 was also upgraded to use an aluminium casing and end-cap, replacing the plastic versions used during LEACOAST2.
During the bench test, no problems were encountered although the compasses on instruments G250+B252 and G258+B233 needed re-orienting for sideways mounting. Compass checks were carried out prior to deployment and the necessary offsets corrected. The ADVs were set up using the factory calibrations supplied to POL technical staff. The instruments were set for 16 Hz recording at 20 minute bursts each hour on the hour using an external pulse from the SyncGen3 central timing clock. All three systems were set to record using ENU coordinates not the normal XYZ, at the Principal Scientific Officer (PSO)'s request.
Data Processing
After the instruments were recovered on cruise PD06_07, the data were downloaded from the loggers by POL staff and processed using Sontek ViewHydraPro software to generate MATLAB .MAT format files for analysis.
Processing Undertaken by BODC: ADV data on POLRIG994
BODC Processing
The data were supplied to BODC by the Data Originator as Matlab format .MAT files. These were reformatted to the BODC internal QXF format using BODC transfer function 390. The following table shows how the variables within the .MAT files were mapped to appropriate BODC parameter codes:
| Matlab Variable | Units | BODC Parameter Code | Units | Description | Comment |
|---|---|---|---|---|---|
| Amp1 | dB | ASAMSTK1 | dB | Signal return amplitude from the water body by SonTek current meter beam 1 | - |
| Amp2 | dB | ASAMSTK2 | dB | Signal return amplitude from the water body by SonTek current meter beam 2 | - |
| Amp3 | dB | ASAMSTK3 | dB | Signal return amplitude from the water body by SonTek current meter beam 3 | - |
| Amp_StD_1 | dB | ASAMSDK1 | dB | Signal return amplitude standard deviation from the water body by SonTek current meter beam 1 | - |
| Amp_StD_2 | dB | ASAMSDK2 | dB | Signal return amplitude standard deviation from the water body by SonTek current meter beam 2 | - |
| Amp_StD_3 | dB | ASAMSDK3 | dB | Signal return amplitude standard deviation from the water body by SonTek current meter beam 3 | - |
| Heading | degrees | HEADCMMG | degrees | Orientation (horizontal relative to magnetic north) of measurement platform {heading} by compass | Cross-checked by Data Originator against independent compass readings before deployment |
| Heading_StD | degrees | HEADSD01 | degrees | Orientation standard deviation (horizontal) of measurement platform {heading standard deviation} by compass | - |
| Pitch | degrees | PTCHEI01 | degrees | Orientation (pitch) of measurement platform by inclinometer | - |
| Pitch_StD | degrees | PTCHSD01 | degrees | Orientation standard deviation (pitch) of measurement platform by inclinometer | - |
| Press | dbar | PREXSTEK | dbar | Pressure mean (measured variable) exerted by the water body by semi-fixed moored SonTek current meter | - |
| Press_StD | dbar | SDPRSTEK | dbar | Pressure standard deviation (measured variable) exerted by the water body by semi-fixed moored SonTek current meter | - |
| Roll | degrees | ROLLEI01 | degrees | Orientation (roll angle) of measurement platform by inclinometer | - |
| Roll_StD | degrees | ROLLSD01 | degrees | Orientation standard deviation (roll angle) of measurement platform by inclinometer | - |
| Temp | degrees C | TEMPSTEK | degrees C | Temperature mean of the water body by SonTek current meter | - |
| Temp_StD | degrees C | TEMPSDEK | degrees C | Temperature standard deviation of the water body by SonTek current meter | - |
| Vel1 | cm s-1 | LCEWSTEK | cm s-1 | Eastward current velocity (Eulerian relative to magnetic north) in the water body by SonTek current meter | - |
| Vel2 | cm s-1 | LCNSSTEK | cm s-1 | Northward current velocity (Eulerian relative to magnetic north) in the water body by SonTek current meter | - |
| Vel3 | cm s-1 | LRZASTEK | cm s-1 | Upward current velocity in the water body by SonTek current meter | - |
| vel_StD_1 | cm s-1 | SDEWSTEK | cm s-1 | Eastward current velocity standard deviation in the water body by SonTek current meter | - |
| vel_StD_2 | cm s-1 | SDNSSTEK | cm s-1 | Northward current velocity standard deviation in the water body by SonTek current meter | - |
| vel_StD_3 | cm s-1 | SDZASTEK | cm s-1 | Upward current velocity standard deviation in the water body by SonTek current meter | - |
The data were screened by BODC using their in-house EDSERPLO visualisation software and any anomalous data were flagged.
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:
- Irregularities such as unfeasible values
- Inconsistencies between related information, for example:
- Times for instrument deployment and for start/end of data series
- Length of record and the number of data cycles/cycle interval
- Parameters expected and the parameters actually present in the data cycles
- Originator's comments on meter/mooring performance and data quality
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:
- Spurious data at the start or end of the record.
- Obvious spikes occurring in periods free from meteorological disturbance.
- A sequence of constant values in consecutive data cycles.
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:
- Maximum and minimum values of parameters (spikes excluded).
- The occurrence of meteorological events.
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
Proudman Oceanographic Laboratory Dee Experiment
Introduction
Sediment transport process models are a vital tool in allowing scientists to predict sediment transport and forecast seabed and coastal morphodynamic evolution. It is however, difficult to obtain accurate models due to the complex inter-dependence of sediment processes in the bottom boundary layer. This inter-dependence is governed by interactions between the sediment transport triad; the bed, the hydrodynamics and the mobile sediments.
Scientific Objectives
- To use a varying suite of instruments to make co-located measurements of the sediment triad
- To provide a framework to allow assessment and improvement of the latest sediment transport models
- To address dynamics of suspended sediments in terms of supply of material to the coastal zone from estuaries
- Development of a new description of suspended sediment and water opacity to improve simulation of coastal primary productivity
Fieldwork
The study site chosen by POL for this research was the Dee Estuary, Liverpool Bay. POL performed fieldwork in the Hilbre Channel on the eastern side of the Estuary and the Welsh Channel on the western exit of the Estuary, with emphasis placed on two repeat stations, HC and WC. The fieldwork started in February 2005 and has been summarised below:
| Cruise | Dates | Hilbre Channel | Welsh Channel |
|---|---|---|---|
| PD03_05 | 2005-02-03 to 2005-02-04 | 25 hour CTD station 3 x mooring deployments | 13 hour CTD station 1 mooring deployment |
| PD07_05 | 2005-03-03 to 2005-03-04 | 23 hour CTD station Mooring recovery | 19 hour CTD station Mooring recovery |
| PD05_06 | 2006-02-08 to 2006-02-10 | 24 hour CTD station 2 x mooring deployment | 22 hour CTD station 1 mooring deployment |
| PD09_06 | 2006-03-06 to 2006-03-09 | 23 hour CTD station Mooring recovery | 25 hour CTD station Mooring recovery |
| PD04_07 | 2007-03-13 to 2007-03-16 | 25 hour CTD station 2 x mooring deployment | 25 hour CTD station 1 mooring deployment |
Funding
The Dee Experiment project was core funded by POL under Programme 2 (Shallow coastal seas) Theme 5 (Coastal and sediment processes) of POL's Science Programme 2001 - 2006. From March 2007 onwards, this core funding was replaced by funding from NERC's Oceans 2025 programme and the Dee Experiment research continued as part of Oceans 2025 Work Package 3.3.
Data Activity or Cruise Information
Data Activity
| Start Date (yyyy-mm-dd) | 2007-03-13 |
| End Date (yyyy-mm-dd) | 2007-04-19 |
| Organization Undertaking Activity | Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool) |
| Country of Organization | United Kingdom |
| Originator's Data Activity Identifier | 263 |
| Platform Category | fixed benthic node |
Dee Experiment mini-STABLE deployment POLRIG944
The mini-STABLE benthic frame was deployed in the Dee Estuary, Liverpool Bay as part of the UK Proudman Oceanographic Laboratory (POL) Dee Experiment. The mooring was deployed at Site WC from 14:34 UTC 13 March 2007 to 08:29 UTC 19 April 2007.
Deployment and recovery information
| Deployment cruise | RV Prince Madog 04_07 |
|---|---|
| Recovery cruise | RV Prince Madog 06_07 |
| Rig latitude (+ve N) | 53.36745 |
| Rig longitude (+ve E) | -3.32335 |
| Water depth (m) | 16.4 |
The mini-STABLE frame was of a tripod design (see image) with the following overall dimensions (all measurements +/- 0.005 m):
| Height : | 1.375 m |
| Separation of legs (top) : | 1.51 m |
| Separation of legs (bottom) : | 2.16 m |
| Front to back : | 1.44 m |
| Height to centre of lowest cross-member : | 1.065 m |
(Image courtesy of Dr. Richard Cooke, POL (2007))
The instrumentation mounted on mini-STABLE during this deployment is detailed in the below table:
| SonTek ADVOcean/Hydra Acoustic Doppler Velocimeter (ADV) comprising logger G258 + probe B233 |
| SonTek ADVOcean/Hydra ADV comprising logger G250 + probe B252 |
| SonTek ADVOcean/Hydra ADV comprising logger G412 + probe B331 |
| POL Acoustic backscatter sensor ABS3 |
| SyncGen3 central timing clock |
| Marine Electronics Sand Ripple Profiling Sonar with external battery pack and adjusted acoustic frequency of 1.1 MHz |
| RD Instruments Workhorse Monitor 1.2 MHz Acoustic Doppler Current Profiler (ADCP) #6489 with external battery pack |
| Sequoia LISST-100ST configured as LISST-100 |
| University of East Anglia (UEA) sediment trap |
The ADVs were mounted at separate heights on a vertical pole with each transmitter axis pointing horizontally, i.e. perpendicular to the sea surface/sea bed. The heights above the bed are as follows:
| Instrument | Height above bed (m) |
|---|---|
| G258 + B233 | 0.3 |
| G250 + B252 | 0.5 |
| G412 + B331 | 0.7 |
Other Series linked to this Data Activity - 844847 844860
Cruise
| Cruise Name | PD04/07 |
| Departure Date | 2007-03-13 |
| Arrival Date | 2007-03-16 |
| Principal Scientist(s) | Alejandro J Souza (Proudman Oceanographic Laboratory) |
| Ship | RV Prince Madog |
Complete Cruise Metadata Report is available here
Fixed Station Information
Fixed Station Information
| Station Name | Dee Estuary Station WC |
| Category | Offshore area |
| Latitude | 53° 22.12' N |
| Longitude | 3° 19.68' W |
| Water depth below MSL | 12.0 m |
Dee Estuary Station WC
This station is located within the Welsh Channel of the Dee Estuary, Liverpool Bay. It is one of two stations repeatedly visited by the Proudman Oceanographic Laboratory (POL) in the Dee. All activities at this site occurred within a box bounded by co-ordinates 53.371°N, 3.31791°W at the north-east corner and 53.36642°N, 3.33817°W at the south-west corner. Typical depth ranges encountered within the box are 7 m - 17 m.
POL activites can be separated into two groups. These are (i) repeat CTD profiles over tidal cycles; (ii) mooring deployments.
The deployment history, to date, for this station is summarised below:
| Cruise | Start Date | End Date | Casts |
| PD07_04 | 2004-03-04 | 2004-03-05 | 23 |
| PD11_04A | 2005-03-29 | 2005-03-30 | 26 |
| PD03_05 | 2005-02-03 | 2005-02-04 | 27 |
| PD07_05 | 2005-03-03 | 2005-03-04 | 40 |
| PD05_06 | 2006-02-10 | 2006-02-10 | 44 |
| PD09_06 | 2006-03-08 | 2006-03-09 | 50 |
| PD04_07 | 2007-03-13 | 2007-03-14 | 50 |
| PD06_07 | 2007-04-18 | 2007-04-19 | 23 |
| PD04_08 | 2008-02-12 | 2008-02-13 | 41 |
| PD07_08 | 2008-03-13 | 2008-03-13 | 5 |
| PD02_09A | 2009-02-03 | 2009-02-04 | 45 |
| PD06_09 | 2009-03-03 | 2009-03-04 | 39 |
| PD16_09 | 2009-05-06 | 2009-05-07 | 29 |
| PD22_09 | 2009-06-02 | 2009-06-03 | 37 |
The CTD instrument package for these cruises was a Sea-Bird 911plus, with beam transmissometer, fluorometer, LICOR PAR sensor, LISST-25, and oxygen sensor.
The mooring deployment history for this site is as follows:
| Coverage | Instruments |
| February to March 2005 | 1.2 MHz ADCP, LISST-100C |
| February to March 2006 | 1.2 MHz ADCP, LISST-100C |
| February to March 2007 | 1.2 MHz ADCP, 2D ripple profiler, ABS, ADV x 3, LISST-100C, settling tube |
| February to March 2008 | 600 kHz ADCP, 2D ripple profiler, ABS, ADV x 3, LISST-100C |
| February to June 2009 | 1.2 MHz ADCP, 2D ripple profiler, ABS, ADV x 3, LISST-100X, SBE-37 MicroCAT x 2, settling tube |
Key:
ADCP: Acoustic Doppler Current Profiler
ABS: Acoustic Backscatter Sensor
ADV: Acoustic Doppler Velocimeter
LISST: Laser In-Situ Scattering Transmissometer
SBE-37 MicroCAT: Conductivity and Temperature Sensor
Other Series linked to this Fixed Station for this cruise - 844847 844860 969694 969701 969713 969725 969737 969749 969750 969762 969774 969786 969798 969805 969817 969829 969830 969842 969854 969866 969878 969891 969909 969910 969922 969934 969946 969958 969971 969983 969995 970007 970019 970020 970032 970044 970056 970068 970081 970093 970100 970112 970124 970136 970148 970161 970173 970185 970197 970204 970216 970228
Other Cruises linked to this Fixed Station (with the number of series) - PD02/09A (45) PD04/07 (52) PD04/08 (41) PD06/07 (23) PD06/09 (38) PD07/08 (5)
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 |
