Metadata Report for BODC Series Reference Number 1623064


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI Workhorse Sentinel-600 ADCP  current profilers
Instrument Mounting subsurface mooring
Originating Country United Kingdom
Originator Dr Matt Palmer
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Project(s) Coastal Observatory
 

Data Identifiers

Originator's Identifier BB2390.00952
BODC Series Reference 1623064
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2006-02-06 12:30
End Time (yyyy-mm-dd hh:mm) 2006-04-05 12:10
Nominal Cycle Interval 600.0 seconds
 

Spatial Co-ordinates

Latitude 53.44800 N ( 53° 26.9' N )
Longitude 3.63900 W ( 3° 38.3' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 0.0 m
Maximum Sensor Depth 20.9 m
Minimum Sensor Height 2.7 m
Maximum Sensor Height 23.6 m
Sea Floor Depth 23.6 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 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
HBINAA01 0 Metres BinHeight Height above bed (ADCP bin) in the water body
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)
ASLVMWHA 1 Metres SL_MWH_ADCP Surface elevation (Mean Water Height) of the water body by acoustic doppler current profiler (ADCP)
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

No Problem Report Found in the Database

Originator's quality control comments for PD04_06 COBS moorings

Data supplied to BODC were accompanied by data quality notes from the Originator that detailed observations made when the data were processed and subsequent processing decisions. A summary of these notes have been provided in the tables below.

Rig#951


Instrument Serial number Instrument depth Data quality comments
Sea-Bird 16+ SEACAT fitted with Seapoint Turbidity Meter 10487 04596 Located on seabed This instrument was deployed on cruise PD09_06, because bad weather prevented it from being deployed on PD04_06. There was no deployment CTD available for quality control. No offsets were found in temperature and conductivity when these data were compared to CTD data recorded when the mooring was recovered.

Rig#952


Instrument Serial number Instrument depth Data quality comments
Sea-Bird 16+ SEACAT fitted with Seapoint Turbidity Meter 10489 04737 Located on seabed All conductivity cycles recorded after 2006-03-26 06:00:03 have been converted to absent data values, due to a problem in this channel after this date. Comparisons performed against CTD data found a temperature offset of +0.0055°C, however no adjustments were made to the data file because the size of this offset was smaller than the target accuracy of +0.01°C.

Rig#958


Instrument Serial number Instrument depth Data quality comments
Sea-Bird MicroCAT 02081 5 m Recovery CTD comparison checks (no CTD was available at deployment) revealed the temperature and conductivity data to be of good quality. Salinity values have been changed by -0.02 after comparing these data with the data from other instruments present at this site.
Sea-Bird MicroCAT 02010 10 m Comparisons performed against CTD data found possible offsets in these data, but due to the separation distance between the CTD and mooring (greater than one kilometre) no adjustments have been made to these data. Salinity values have been changed by -0.04 after comparing these data with data from other instruments present at this site.
Teledyne RDI 600 kHz ADCP 2391 Located on seabed To correct for the magnetic declination (difference between magnetic north and true north) latitude values were changed by -4.212°. All latitude values were modified by -3.2147° to correct for the compass error.

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

Teledyne RDI Workhorse Sentinel 600 kHz Acoustic Doppler Current Profiler (ADCP)

The Workhorse Sentinel is a self-contained ADCP that can be used either on a mooring or mounted in the hull of a moving vessel. Its 4-beam design provides a redundant data source (in case of a blocked or damaged beam), an independent data quality measure (error velocity) and reduces the variance in data, thereby improving data reliability, quality and accuracy.

Real-time data can be transmitted to shore via a cable link or acoustic modem or they can be stored internally. Sensors for bottom tracking, pressure and directional wave measurements can be added to the instrument and a special casing is available for deeper applications.

Specifications

Typical range 50 m
Number of depth cells 1 to 128
Typical ping rate 2 Hz
Standard depth rating 200 to 6000 m
Beam angle 20 °
Echo intensity profile
Dynamic range 80 dB
Precision ± 1.5 dB
Velocity
Accuracy 0.3% of the water velocity relative to the ADCP ± 0.3 cm s -1
Resolution 0.1 cm s -1
Range

± 5 m s -1 (default)

± 20 m s -1 (maximum)

Vertical resolution Range / Std Dev
for 0.5 m 39 m / 12.9 cm s -1
for 1 m 43 m / 6.1 cm s -1
for 2 m 47 m / 3.0 cm s -1
for 4 m 52 m / 2.0 cm s -1
Long Range mode
Range 70 m
Depth cell size 4 m
Std Deviation 4.2 cm s -1
Temperature
Operating temp. -5 to 45 °C
Precision ± 0.4 °C
Resolution 0.01 °C
Tilt
Range ± 15 °
Accuracy ± 0.5 °
Precision ± 0.5 °
Resolution 0.01 °
Compass
Accuracy ± 2 °
Resolution 0.01 °
Maximum tilt ± 15 °
Precision ± 0.5 °

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

BODC Processing document for Coastal Observatory moored ADCP data

The data arrived at BODC as 117 ASCII format .dat files representing moored ADCP data recorded at the Coastal Observatory sites 1(9), 20 and 21 between 07 August 2002 and 20 September 2011. Following standard BODC procedure the files were reformatted into BODC standard internal format using an internal transfer function. This included removing surface null bins.

The following table shows how the originator's variables were mapped to the appropriate BODC parameter codes:

Originator's variable Units Description BODC parameter code Units Comments
Sea surface height m Surface elevation (Mean Water Height) of the water body by acoustic doppler current profiler (ADCP) ASLVMWHA Metres -
East cm/s Eastward current velocity (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP) LCEWAP01 cm s -1 -
North cm/s Northward current velocity (Eulerian) in the water body by moored acoustic doppler current profiler (ADCP) LCNSAP01 cm s -1 -
Vertical cm/s Upward current velocity in the water body by moored acoustic doppler current profiler (ADCP) LRZAAP01 cm s -1 -
Error cm/s Current velocity error in the water body by moored acoustic doppler current profiler (ADCP) LERRAP01 cm s -1 -
3beam_matrix None - - - Boolean value stating whether the data originator had performed the three beam correction on a particular bin. Values indicating that the three beam correction had been performed were converted into an originator's flag ('L') when the data were transferred into qxf format.
Height from sea bed m Height above bed (ADCP bin) in the water body HBINAA01 Metres -

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.

COBS RDI Teledyne 600 kHz ADCP Data Processing

Sampling Strategy

Two mooring sites were maintained for the duration of the Liverpool Bay Coastal Observatory project. Moored instruments present at Site A (also known as Site 1/9) through the entire data collection phase of the observatory. From 05 April 2005 (Cruise PD11_05) moorings were also present at an additional Site B. From April 2005 until December 2009 mooring Site B was located at Coastal Observatory Station 20. The moorings were moved to Station 21 from January 2010, where they remained until the end of the observatory.

Originator's Processing

The raw ADCP data were processed using the standard RDI software bblist which resulted in the creation of two files, the first containing the current velocities separated by bin depth and an auxiliary file containing the variables heading, pitch, roll, temperature and pressure. The variables present in the auxiliary files were only used for quality control purposes with the exception of pressure, which was used to calculate sea surface height taking into account the latitude and the height of the transducer head above the seabed, which was estimated to be 0.7 m. Sea surface height and the current velocity data were then combined into one file.

Before the data were supplied to BODC, some quality control procedures were performed by the Data Originator. First the Originator corrected the latitude values to take into account the difference between magnetic north and true north (magnetic declination). The Originator also corrected the latitude values for compass error caused by localised magnetic fields such as the ADCP frame and battery, using HF radar data recorded by two HF radars located at Abergele and Formby as a reference. Once compass errors for all ADCP series recorded at Site A had been calculated, a mean of all errors was taken. As the ADCP compass error is a random error, the expected mean of all errors is approximately 0°, however the Originator found that the actual mean compass error was approximately 5.3°. All compass errors were therefore modified by 5.3°. The compass error values given in the Originator's data processing documents have taken this adjustment into account.

The bins recorded above the sea surface were then converted to absent data indicators by the Data Originator. If there were any problems with the pressure data recorded by the ADCP, then data from another instrument attached to the same frame was used instead. If no pressure records were available, then backscatter intensity was used to calculate the sea surface. The top three bins have been removed in all series to remove noise in these data caused by side lobe contamination. A more detailed explanation of all of the quality control procedures performed before the data were submitted to BODC can be found in the Originator's ADCP quality control methodology document.

Analysis of the Coastal Observatory ADCP data found that some of the midwater beams had been contaminated, with the Originator suspecting that the cause was the contamination of individual acoustic beams by the recovery line attached to the ADCP lander frame. As the contamination only affected individual acoustic beams, it was possible to estimate the horizontal component of the contaminated beam using the vertical components of the two perpendicular beams and the unaffected horizontal component. A full description of how this procedure was carried out can be found in the Originator's ADCP correction report

Finally a visual inspection of the data was carried out to find any obvious errors which had not been corrected by the previous quality control checks.


Project Information

Proudman Oceanographic Laboratory Coastal Observatory

The Coastal Observatory was established by Proudman Oceanographic Laboratory as a coastal zone real time observing and monitoring system. The main objective is to understand a coastal sea's response both to natural forcing and to the consequences of human activity. Near real-time measurements will be integrated with coupled models into a pre-operational coastal prediction system whose results will be displayed on the World Wide Web.

The Observatory is expected to grow and evolve as resources and technology allow, all the while building up long time series. A site selection pilot study was carried out in September 2001 and the Observatory became operational in August 2002.

The site is located in Liverpool Bay and is subject to typical coastal sea processes, with strong tides, occasional large storm surges and waves, freshwater input, stable and unstable stratification, high suspended sediment concentration and biogeochemical interaction. Measurements and monitoring will focus on the impacts of storms, variations in river discharge (especially the Mersey), seasonality and blooms in Liverpool Bay.

A variety of methods will be used to obtain measurements, including:

  1. Moored instruments for in situ time series of currents, temperature and salinity profiles, and surface waves and meteorology. It is hoped that turbidity and chlorophyll measurements will be made at another site as the Observatory progresses;
  2. The Cefas Smartbuoy for surface properties such as nutrients and chlorophyll, starting late 2002;
  3. R.V. Prince Madog to carry out spatial surveys and service moorings;
  4. Instrumented ferries for near surface temperature, salinity, turbidity, chlorophyll and nutrients. The first route will be Liverpool to Douglas, Isle of Man, starting late 2002;
  5. Drifters for surface currents and properties such as temperature and salinity, starting in 2004;
  6. Tide gauges, with sensors for meteorology, waves, temperature and salinity, where appropriate;
  7. Meteorological data from Bidston Observatory and Hilbre Island, HF radar and tide gauge sites;
  8. Shore-based HF radar measuring waves and surface currents out to a range of 50 km, starting in 2003;
  9. Satellite data, with infrared for sea surface temperature and visible for chlorophyll and suspended sediment.

The partners currently involved with the project are listed below:

A summary of Coastal Observatory cruises to date on R.V. Prince Madog is given in the table below:

Year No. of cruises Work summary
2001 1 Site selection and pilot study. 95 CTD casts.
2002 4 POL moorings deployed and serviced
Cefas Waverider and SmartBuoy deployed and serviced
103 CTD casts
2003 10 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
341 CTD/LISST casts
2004 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
347 CTD/LISST casts
2005 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
268 CTD/LISST casts
2006 11 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
508 CTD/LISST casts
2007 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
471 CTD/LISST casts
2008 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
260 CTD/LISST casts
2009 7 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
213 CTD/LISST casts
2010 8 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
268 CTD/LISST casts
2011 6 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
307 CTD/LISST casts to date, ongoing

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2006-02-06
End Date (yyyy-mm-dd) 2006-04-05
Organization Undertaking ActivityProudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPOLRIG#952
Platform Categoryfixed benthic node

Proudman Oceanographic Laboratory Rig#952

Deployment and Recovery

This rig was deployed as part of the Liverpool Bay Coastal Observatory during R.V. Prince Madog cruise PD04_06. Recovery of the rig took place during R.V. Prince Madog cruise PD12_06.

Recovery of the rig was not quite straightforward, as the ADCP frame did not surface after the first time the release was fired. There was no indication that the ADCP had moved since deployment and it eventually surfaced with the aid of a loop wire. One of the pellets was recovered (the other had no rope through it) followed by the frame and the ballast weight.

Deployment details are given in the table below. Date and time are in Universal Time (UT) and are displayed in the ISO format YYYY-MM-DD hh:mm.


Rig Position 53° 26.88' N, 3° 38.34' W
Water Depth 23.6 m
Deployed (UT) 2006-02-06 12:30
Recovered (UT) 2006-04-05 10:04
No. of Days 58

Rig Description

This rig was a bottom frame with the following instruments mounted 0.5 m above the sea bed: Waves Acoustic Doppler Current Profiler (ADCP), Sea-Bird 16plus, Telemetry ADCP and a Telemetry buoy with a LinkQuest modem. The frame was fitted with two Benthos releases with fizz links and a spooler with 200 m of rope for recovery of the ballast weight.


Instrument Serial Number Parameters Measured Sampling Description Comments
RDI Waves ADCP 600 kHz 2390 Horizontal current velocity components
Vertical current velocity components
Temperature
Pressure
Mode 1: 100 pings every 10 minutes (velocity standard deviation 0.007 m s-1).
35 x 1 m bins (2.65 - 36.65 m above the bed).
Sound velocity calculated from temperature, depth and salinity of 32.
Fitted with a pressure sensor and 1 Gbyte PCMCIA memory; hourly wave recording enabled.
Sea-Bird 16plus V RS-485 1.0 4737 Temperature
Conductivity
Pressure
Turbidity
Sample interval 600 s. Fitted to base of frame with pumped conductivity sensor underneath.
SeaPoint turbidity sensor: S/N 10489 taped to roll bar; set up for 0 - 125 FTU range.
RDI Telemetry ADCP 1.2 MHz 0572 Horizontal current velocity components
Vertical current velocity components
Temperature
Pressure
Mode 1: 100 pings every 10 minutes (velocity standard deviation 0.003 m s-1). Fitted with an Orbcomm satellite system and a LinkQuest acoustic modem (serial number 8602).

Other Series linked to this Data Activity - 696363

Cruise

Cruise Name PD04/06
Departure Date 2006-02-06
Arrival Date 2006-02-07
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 NameCoastal Observatory Site 21
CategoryOffshore location
Latitude53° 27.13' N
Longitude3° 38.48' W
Water depth below MSL25.0 m

Liverpool Bay Coastal Observatory Site 21

This station is one of 34 stations regularly visited by the Proudman Oceanographic Laboratory (POL) as part of the Liverpool Bay Coastal Observatory. The main activity at this site are CTD profiles (since August 2002) which are taken during each site visit. This station was also the secondary mooring site (also referred to as Site B) for the Coastal Observatory project between April 2005 and March 2010. After March 2010 the moorings were moved to site 20. The station lies within a box of mean water depth 24 m with the following co-ordinates:

Box Corner Latitude (+ve North) Longitude (+ve East)
North-west corner 53.46028 -3.658
South-east corner 53.44249 -3.6105

The position of this station relative to the other POL Coastal Observatory sites can be seen from the figure below.

BODC image

Mooring Deployment History

2010

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, Telemetry ADCP 1088, 1092, 1096, 1100, 1104, 1107, 1111 January - December
SmartBuoy CT, FL, OBS, BD 1087, 1091, 1095, 1099, 1103, 1110, 1115 January - December

2009

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, Telemetry ADCP 1057, 1065, 1069, 1072, 1076, 1080, 1084 January - December
SmartBuoy CT, FL, OBS, BD 1056, 1064, 1068, 1075, 1079, 1083 January - December

2008

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, Telemetry ADCP 1026, 1030, 1033, 1038, 1053 January - December
SmartBuoy CT, FL, OBS, BD LB2_023/1025, LB2_024/1029, LB2_025/1034, LB2_026/1037, LB2_029/1052 January - December

2007

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, Telemetry ADCP 992, 999, 1002, 1007, 1012, 1019 January - December
SmartBuoy CT, FL, OBS, BD 991, LB2_016/998, LB2_017/1003, LB2_018/1006, LB2_019/1011, LB2_020/1015, LB2_021/1018, LB2_022/1022 January - December

2006

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, Telemetry ADCP 952, 960, 964, 968, 972, 976, 980, 984, 988 January - December
SmartBuoy CT, FL, OBS, BD LB2_006, LB2_007, LB2_008, LB2_009, LB2_010, LB2_011, LB2_012, LB2_013/983, LB2_014/987 January - December

2005

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS 923, 927, 931, 936, 940, 943, 947, 950 January - December
SmartBuoy CT, FL, OBS, WMS LB2_001/926, LB2_002/930, LB2_003/935, LB2_004/939, LB2_005/946 May - December
Marker buoy CT 922 April - May

CTD Sampling History

Year Number of Cruises Total Casts per year
2011 5 5
2010 6 6
2009 7 18
2008 9 16
2007 8 17
2006 9 18
2005 9 14
2004 8 8
2003 9 9
2002 2 2

The CTD instrument package for these cruises was a Sea-Bird 911plus, with beam transmissometer, fluorometer, LICOR PAR sensor, LISST-25, and oxygen sensor.

Key

ADCP = Acoustic Doppler Current Profiler
BD = Bacterial degradation experiment
CT = Conductivity and temperature logger
CTD = Conductivity, temperature, depth sensor
FL = Fluorometer
OBS = Optical Backscatter Turbidity meter
Telemetry ADCP = ADCP sending data back to shore in real-time
WMS = Automatic water sampler

Other Series linked to this Fixed Station for this cruise - 679396 679403 696363

Other Cruises linked to this Fixed Station (with the number of series) - PD01/08 (12) PD01/11 (1) PD02/07 (4) PD02/09B (11) PD02/10 (1) PD04/07 (4) PD06/07 (9) PD07/08 (9) PD07/11 (1) PD09/07 (9) PD09/08 (11) PD11/05 (3) PD11/11 (1) PD12/06 (4) PD12/09 (11) PD13/07 (11) PD14/08 (10) PD16/06 (4) PD16/07 (10) PD17/10 (5) PD18/05 (8) PD18/09 (10) PD19/08 (2) PD20/06 (4) PD20/07 (7) PD21/05 (8) PD21/10 (1) PD22/06 (4) PD23/07 (10) PD23/08 (7) PD24/09 (5) PD25/05 (8) PD25/06 (4) PD27/07 (9) PD29/06 (4) PD29/08 (9) PD29/10 (1) PD30/05 (7) PD33/08 (1) PD33/09 (12) PD34/05 (2) PD35/06 (7) PD36/10 (1) PD37/06 (7) PD37/08 (11) PD38/09 (9) PD41/05 (6) PD43/11 (1) PD47/09 (11) PD48/05 (2) PD49/10 (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