Metadata Report for BODC Series Reference Number 1623617


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) Oceans 2025 Theme 10 SO11
 

Data Identifiers

Originator's Identifier BB3644.01046
BODC Series Reference 1623617
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2008-09-10 16:34
End Time (yyyy-mm-dd hh:mm) 2008-11-30 04:41
Nominal Cycle Interval 600.0 seconds
 

Spatial Co-ordinates

Latitude 53.45017 N ( 53° 27.0' N )
Longitude 3.64333 W ( 3° 38.6' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 0.0 m
Maximum Sensor Depth 21.95 m
Minimum Sensor Height 2.65 m
Maximum Sensor Height 24.6 m
Sea Floor Depth 24.6 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 PD29_08 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#1043

Instrument Serial number Instrument depth Data quality comments
Sea-Bird MicroCAT 05793 5 m There was no deployment CTD to perform CTD comparison checks, however the quality of the temperature and conductivity data appears to be satisfactory.
Star-Oddi minilogger 02842 7.5 m The temperature data recorded by this sensor was offset by -0.03°C when compared to the Sea-Bird MicroCATs and Sea-Bird 16plus at this site. All temperature values have been adjusted by +0.03°C to compensate for this offset.
Sea-Bird MicroCAT 05792 10 m All conductivity data recorded between 2008-10-29 08:00:00 UTC and 2008-11-07 05:10:00 UTC has been converted to absent data values.
Star-Oddi minilogger 02843 15 m The temperature data recorded by this sensor was offset by -0.01°C when compared to the Sea-Bird MicroCATs and Sea-Bird 16plus at this site. All temperature values have been adjusted by +0.01°C to compensate for this offset.

Rig#1044


Instrument Serial number Instrument depth Data quality comments
Sea-Bird 16+ SEACAT fitted with Seapoint Turbidity Meter #10471 05309 Located on seabed All conductivity data recorded after 2008-10-05 00:00:03 UTC have been converted into absent data values by the Data Originator. After these data were compared to the other instruments present at this site, an offset of -0.14 was found in the salinity channel. All salinity values were adjusted by +0.14 to compensate for this offset.
Teledyne RDI 600 kHz ADCP 5803 Located on seabed To correct for the magnetic declination (difference between magnetic north and true north) latitude values were changed by -3.4777°. All latitude values were modified by -2.6393° to correct for the compass error.

Rig#1045

Instrument Serial number Instrument depth Data quality comments
Sea-Bird MicroCAT 05791 5 m There was no deployment CTD available to perform CTD comparison checks, however the other CTD checks found small offsets in temperature and conductivity. No adjustments have been made to these data.
Star-Oddi minilogger 02847 7.5 m The temperature data recorded by this sensor was offset by -0.02°C when compared to the Sea-Bird MicroCATs and Sea-Bird 16plus at this site. All temperature values have been adjusted by +0.02°C to compensate for this offset.
Sea-bird MicroCAT 05433 10 m None.
Star-Oddi minilogger 02849 15 m The temperature data recorded by this sensor was offset by -0.02°C when compared to the Sea-Bird MicroCATs and Sea-Bird 16plus at this site. All temperature values have been adjusted by +0.02°C to compensate for this offset.

Rig#1046


Instrument Serial number Instrument depth Data quality comments
Sea-bird 16+ SEACAT fitted with Seapoint Turbidity Meter #10320 05310 Located on seabed This series was cut short due to a battery failure on 2008-11-24. The shape of this profile is similar to MicroCAT 05433 which suggests the data may be good quality, there was only one CTD cast available to perform comparison checks, so the Data Originator recommends that these data are used with caution. Pressure was unrealistic after 02-11-2008 23:00:03 UTC and has been converted into absent data values by the Data Originator.
Teledyne RDI 600 kHz ADCP 3644 Located on seabed
  • To correct for the magnetic declination (difference between magnetic north and true north) latitude values were changed by -3.5796°.
  • All latitude values were modified by -6.1161° to correct for the compass error.
  • The ADCP's pressure sensor became blocked on 2008-10-11 01:14:47 UTC. Pressure data recorded after this date have been set to absent data values by the Data Originator. Before 2008-10-11 01:14:47 UTC the Originator used the pressure data to calculate the sea surface height. After this date the Originator used backscatter intensity.

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. 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 -
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.

Prior to cruise PD33_08 the data originator had been correcting the mid-water current velocities to account for contamination caused by the recovery line attached to the ADCP lander frame. The mooring design was changed from PD33_08, and this redesign successfully eradicated the beam contamination issues that had affected previous deployments. Therefore, no three-beam correction has been applied to these data. This issue is explained in detail in the originator's ADCP correction report , however as previously stated no three-beam correction was applied to these data.

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

Oceans 2025 Theme 10, Sustained Observation Activity 11: Liverpool Bay and Irish Sea Coastal Observatory

Sustained, systematic observations of the ocean and continental shelf seas at appropriate time and space scales allied to numerical models are key to understanding and prediction. In shelf seas these observations address issues as fundamental as 'what is the capacity of shelf seas to absorb change?' encompassing the impacts of climate change, biological productivity and diversity, sustainable management, pollution and public health, safety at sea and extreme events. Advancing understanding of coastal processes to use and manage these resources better is challenging; important controlling processes occur over a broad range of spatial and temporal scales which cannot be simultaneously studied solely with satellite or ship-based platforms.

Considerable effort has been spent by the Proudman Oceangraphic Laboratory (POL) in the years 2001 - 2006 in setting up an integrated observational and now-cast modelling system in Liverpool Bay (see Figure), with the recent POL review stating the observatory was seen as a leader in its field and a unique 'selling' point of the laboratory. Cost benefit analysis (IACMST, 2004) shows that benefits really start to accrue after 10 years. In 2007 - 2012 exploitation of (i) the time series being acquired, (ii) the model-data synthesis and (iii) the increasingly available quantities of real-time data (e.g. river flows) can be carried out through Sustained Observation Activity (SO) 11, to provide an integrated assessment and short term forecasts of the coastal ocean state.

BODC image

Overall Aims and Purpose of SO 11

Measurement and Modelling Activities

More detailed information on this Work Package is available at pages 32 - 35 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/

References:

IACMST., 2004. The Economics of Sustained Marine Measurements. IACMST Information Document, N0.11, Southampton: IACMST, 96 pp


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2008-09-10
End Date (yyyy-mm-dd) 2008-12-11
Organization Undertaking ActivityProudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPOLRIG1046
Platform Categoryfixed benthic node

Proudman Oceanographic Laboratory Rig#1046

Deployment and Recovery

This rig was deployed at Site B as part of the Liverpool Bay Coastal Observatory. Recovery was supposed to take place in October during cruise PD33_08, but due to poor weather conditions, this was postponed until the December cruise, PD37_08.

Deployment cruise RV Prince Madog cruise PD29/08
Recovery cruise RV Prince Madog cruise PD37/08
Rig position 53° 27.014'N 3° 38.603'W
Water Depth 24.6 m

Rig Description

The rig is made up of a bottom frame which was deployed onto the sea bed. Instruments were mounted on the frame, as described in the table below. The frame was fitted with a fizz link, a spooler with 50 m of rope for recovery of the ballast weight and two Benthos releases s/n 70355 (Rx 10.0 kHz, Tx 12.0 kHz, release B) and s/n 72382 (Rx 10.0 kHz, Tx 12.0 kHz, release A).

Instrument Serial Number Meter height above bed (m) Comment
RDI 600 kHz Waves ADCP 3644 0.5 -
RDI 1200 kHz Telemetry ADCP 0572 0.5 -
Sea-Bird 16plus
V RS-232 1.8c
5310 0.5 Instrument fitted to base of frame with pumped conductivity sensor underneath.
SeaPoint turbidity sensor 10320 (0-500 FTU) taped to roll bar.

Other Series linked to this Data Activity - 939219

Cruise

Cruise Name PD29/08
Departure Date 2008-09-10
Arrival Date 2008-09-11
Principal Scientist(s)Phil J Knight (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 - 939219 939232 939244 939300 939312 1024546 1024626 1024706

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) PD04/06 (4) 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) PD29/10 (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