Metadata Report for BODC Series Reference Number 1003634

Metadata Summary

Data Description
Data Category CTD or STD cast
Instrument Type
NameCategories
SeaTech transmissometer  transmissometers
Sea-Bird SBE 13 Dissolved Oxygen Sensor  dissolved gas sensors
Sequoia Laser In-Situ Sediment Size Transmissometer  transmissometers; water temperature sensor; particle sizers
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
LI-COR LI-192 PAR sensor  radiometers
Turner Designs SCUFA II Submersible Fluorometer  fluorometers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Mr Phil Knight
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status QC in progress
Project(s) Coastal Observatory
 

Data Identifiers

Originator's Identifier C001
BODC Series Reference 1003634
 

Time Co-ordinates(UT)
Start Time (yyyy-mm-dd hh:mm) 2006-12-15 08:04
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 0.5 decibars
 

Spatial Co-ordinates

Latitude 53.53300 N ( 53° 32.0' N )
Longitude 3.36567 W ( 3° 21.9' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 1.73 m
Maximum Sensor Depth 22.05 m
Minimum Sensor Height 0.94 m
Maximum Sensor Height 21.27 m
Sea Floor Depth 23.0 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during 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 Title
ATTNMR01 1 per metre Attenuance (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
DOXYPR01 1 Micromoles per litre Concentration of oxygen {O2} per unit volume of the water body [dissolved phase] by in-situ Beckmann probe
FVLTWS01 1 Volts Instrument output (voltage) by linear-response chlorophyll fluorometer
IRRDUV01 1 MicroEinsteins per square metre per second Downwelling vector irradiance as photons (PAR wavelengths) in the water body by cosine-collector radiometer
NVLTLS01 1 Volts Instrument output (voltage) by LISST scatterometer
OXYSBB01 1 Percent Saturation of oxygen {O2} in the water body [dissolved phase] by in-situ Beckmann probe and computation from concentration using Benson and Krause algorithm
POTMCV01 1 Degrees Celsius Potential temperature of the water body by computation using UNESCO 1983 algorithm
PRESPR01 1 Decibars Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALCU01 1 Dimensionless Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
SIGTPR01 1 Kilograms per cubic metre Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPCC01 1 Degrees Celsius Temperature of the water body by CTD and verification against independent measurements
TVLTZR01 1 Volts Instrument output (voltage) by red light transmissometer
 

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

Dissolved Oxygen

All data from this channel should be used with caution as the values measured were unrealistic during this and several other cruises. Readings taken by the probe indicated that the sensor was constantly saturated.

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

Sea Bird Electronics SBE13 Dissolved Oxygen Sensor

The SBE 13 was designed as an auxiliary sensor for Sea Bird SBE 9plus, but can fitted in custom instrumentation applications. When used with the SBE 9 Underwater Unit, a flow-through plenum improves the data quality, as the pumping water over the sensor membrane reduces the errors caused by oxygen depletion during the periods of slow or intermittent flushing and also reduces exposure to biofouling.

The output voltage is proportional to membrane current (oxygen current) and to the sensor element's membrane temperature (oxygen temperature), which is used for internal temperature compensation.

Two versions of the SBE 13 are available: the SBE 13Y uses a YSI polarographic element with replaceable membranes to provide in situ measurements up to 2000 m depth and the SBE 13B uses a Beckman polarographic element to provide in situ measurements up to 10500 m depth, depending on the sensor casing. This sensor includes a replaceable sealed electrolyte membrane cartridge.

The SBE 13 instrument has been out of production since 2001 and has been superseded by the SBE 43.

Specifications

Measurement range 0 to 15 mL L-1
Accuracy 0.1 mL L-1
Time response

2 s at 25°C

5 s at 0°C
Depth range

2000 m (SBE 13Y- housing in anodized aluminum)

6800 m (SBE 13B- housing in anodized aluminum)

105000 m (SBE 13B- housing in titanium)

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

Prince Madog Cruise PD37_06 CTD Instrumentation

The CTD unit was a Sea-Bird Electronics 911plus system (SN P23655-0620), with dissolved oxygen sensor. The rosette sampling system was equipped with 5 litre sampling bottles (manufactured by Ocean Test Equipmetn Inc.). In addition the CTD was fitted with a red (660 nm) beam transmissometer, a fluorometer, a Sequoia Scientific Laser In-Situ Scattering and Transmissometry (LISST) particle analyser and a LI-COR Underwater Quantum Sensor. The Sea-Bird sensors were last calibrated by the manufacturer in January 2004. The table below lists more detailed information about the various sensors.

Sensor Model Serial Number Calibration Date Comments
Pressure transducer Paroscientific Digiquartz 42A-105 76076 21/01/2004 -
Conductivity sensor SBE 4 2543 14/01/2004 -
Temperature sensor SBE 3 P4100 21/01/2004 -
Dissolved oxygen SBE 13 Beckman 130580 05/01/2004 -
Transmissometer 660nm SeaTech T1000 T1021 03/03/1998 20 cm path length
Fluorometer Turner SCUFA II 262 - -
LISST 25A 210 26/10/2006 -
LI-COR LI 192SA 33 - -
Temperature Logger SBE-35 0041 - -

The salinity samples from the CTD were analysed after the cruise using a Portasal salinometer that was calibrated to standard seawater.

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.

Specifications

Specifications for the SBE 9 plus underwater unit are listed below:

Parameter Range Initial accuracy Resolution at 24 Hz Response time
Temperature -5 to 35°C 0.001°C 0.0002°C 0.065 sec
Conductivity 0 to 7 S m-1 0.0003 S m-1 0.00004 S m-1 0.065 sec (pumped)
Pressure 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) 0.015% of full scale 0.001% of full scale 0.015 sec

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

Turner Designs Self-Contained Underwater Fluorescence Apparatus (SCUFA)

The Turner Designs SCUFA is a submersible fluorometer for chlorophyll and dye tracing operations that has been designed to operate in a wide range of concentrations, environmental conditions as well as operational modes (profiling or moored deployments). The instrument includes an integrated temperature probe and software which allow for automatic correction of fluorescence data from temperature effects. The superior ambient light rejection eliminates the effects of sunlight and allows the SCUFA to be used in surface waters without the need for external pumps or light shields.

Each instrument can be customised to meet user requirements. Users can choose one of the following channels: chlorophyll a, cyanobacteria (phycocyanin or phycoerythrin pigments), rhodamine WT, fluorescein and turbidity. Instrument options include turbidity, internal data logging and automatic temperature correction.

Three versions of the SCUFA are available: SCUFA I, II and III. SCUFA I and II are used for chlorophyll a applications, while SCUFA III is used for Rhodamine WT. Models II and III include a turbidity channel that is not present on model I. The SCUFA has been out of production since 2008.

Specifications

Depth rating 600 m
Detector Photodiode
Temperature range -2 to 40°C
Maximum sampling rate

1Hz- digital

5 Hz- analog
Resolution

12 bit- digital

1.2 mV- analog
Dynamic Range
Fluorescence 4 orders of magnitude
Turbidity 3 orders of magnitude

The table below presents the specifications for the different channels.

Specifications Chlorophyll Cyanobacteria Rhodamine WT/Fluorescein
Light source Blue

Orange- PC

Blue- PE

 Green
Excitation/Emission 460/685

595/670 (phycocyanin, PC)

528/573 (phycoerythrin, PE)

530/600 (rhodamine)

490/580 (fluorescein)
Minimum detection Limit
Fluorescence 0.02 µg L-1 150 cells mL-1 0.04 ppb
Turbidity 0.05 NTU 0.05 NTU 0.05 NTU

Further details can be found in the manufacturer's brochure.

LI-COR LI-192 Underwater Quantum Sensor

The LI-192 Underwater Quantum Sensor is used to measure photosynthetic photon flux density and is cosine corrected. The sensor is often referred to as LI-192SA or LI-192SB (the LI-192SB model was superseded by LI-192SA). One of the main differences is that the LI-192SA model includes a built-in voltage output for interfacing with NexSens iSIC and SDL data loggers.

Sensor specifications, current at January 2012, are given in the table below. More information can be found in the manufacturer's LI-192SA andLI-192SB specification sheets.

Sensor Specifications

(Specifications apply to both models unless otherwise stated)

Absolute Calibration ± 5 % in air traceable to NBS.
Sensitivity Typically 3 µA per 1000 µmol s-1 m-2 for LI-192SB and 4 µA per 1000 µmol s-1 m-2 for LI-192SA in water.
Linearity Maximum deviation of 1 % up to 10,000 µmol s-1 m-2.
Stability < ± 2 % change over a 1 year period.
Response Time 10 µs.
Temperature Dependence ± 0.15 % per °C maximum.
Cosine Correction Optimized for both underwater and atmospheric use.
Azimuth < ± 1 % error over 360 ° at 45 ° elevation.
Detector High stability silicon photovoltaic detector (blue enhanced).
Sensor Housing Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications. Waterproof to withstand 800 psi (5500 kPa) (560 meters).

SeaTech Transmissometer

Introduction

The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.

Specifications

Notes

The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

Further details can be found in the manufacturer's Manual.

Sequoia Laser In-situ Sediment Size Transmissometer (LISST)

The Sequoia LISST measures particle size distribution of suspended sediments by laser diffraction. This technique allows particles of various compositions to be measured with a single device and, because the particle volume is roughly of the same order for all sizes, the required dynamic range of the sensors is reduced compared with single-particle counters.

The instrument includes optics for producing a collimated laser beam, a detector array, electronics for signal amplification and processing, a data storage and scheduling computer and a battery system. The primary measurement is the scattering of laser light at a number of angles, which is mathematically inverted to give a grain size distribution, and also scaled to obtain the volume scattering function. The size distribution is presented as concentration in each of 32 logarithmically-spaced grain-size class bins. Optical transmission, water depth and temperature are recorded as supporting measurements.

Several models are available and although the principals of operation are the same, their specifications vary slightly. The specifications for model LISST-100 are provided below.

Specifications

Optical path length

5 cm (standard)

2.5 cm (optional)
Optical transmission 12 bit resolution
Particle size range

Type B: 1.25 to 250 micron diameter

Type C: 2.5 to 500 micron diameter
Resolution 32 size classes, log-spaced
VSF angle range 1.7 to 340 mrad
Maximum sample speed 4 size distributions per second (standard)
Temperature range -10 to 45 °C
Temperature resolution 0.01 °C
Pressure range 0 to 300 m
Pressure resolution 8 cm

Further details can be found in the manufacturer's manual.

Prince Madog Cruise PD37_06 CTD Processing

Sampling Strategy

A total of 4 CTD casts were performed during the cruise in Liverpool Bay. Rosette bottles were fired near-bed on 2 casts in order to obtain independent temperature and salinity samples, the results of which were sent to BODC. Water samples were taken at mid-depth on 3 casts and filtered. The filtrate was stored for trace metal analysis at the Department of Earth and Ocean Sciences, Liverpool University. Additionally, near-surface samples were filtered to determine suspended particulate matter by the School of Ocean Sciences, University of Wales Bangor. Some filtrate was also preserved by mecuric chloride for nutrient analysis by CEFAS.

Data Processing

Data were logged at 24 Hz onto a PC running SEASAVE, Sea-Bird's data acquisition software. The raw Sea-Bird data, configuration and bottle files were supplied to BODC for further processing.

Sea-Bird Processing

The raw CTD files were processed through the Sea-Bird SBE Data Processing software version 5.35. Binary (.DAT) files were converted to engineering units and ASCII format (.CNV) using the DATCNV program. Sea-Bird bottle files (.BTL), with information on pressure and other logged readings at the time of bottle firing, were also generated during the data conversion process.

Sea-Bird software program ALIGNCTD was run to advance conductivity by 0s and oxygen by 3s (within the typical range given in the Sea-Bird manual). No adjustment was made to the temperature channel as the fast sensor response time renders this unnecessary, according to the Sea-Bird literature.

To compensate for conductivity cell thermal mass effects, the data files were run through CELLTM, using alpha = 0.03, 1/beta = 7, typical values for this CTD model given in the Sea-Bird literature. After running WILD EDIT, FILTER was run on the pressure channel using the recommended time filter of 0.15 seconds. Next, a minimum CTD velocity of 0.0 m s-1 was used for LOOP EDIT in order to exclude scans where the CTD was travelling backwards due to ship's heave. Salinity, density and oxygen concentration were then calculated and added to the output files using the DERIVE program. The files were then averaged to 0.5 second intervals using BINAVERAGE.

Reformatting

The data were converted from ASCII format into BODC internal format (QXF). The following table shows the mapping of variables within the original files to appropriate BODC parameter codes:

Originator's Variable Units Description BODC Parameter Code Units Comments
Pressure dbar Pressure exerted by the water body PRESPR01 dbar Calibrated
Conductivity S m-1 Electrical conductivity of the water body by CTD CNDCST01 S m-1 Not banked by BODC. These data are used as an intermediate step in calculation of PSALCU01
Oxygen, Beackman/YSI ml l-1 Dissolved oxygen concentration from Beckman probe DOXYPR01 µmol l-1 ml l-1 * 44.66
Salinity - Practical salinity of the water body PSALCU01 - Uncalibrated
Temperature [ITS-90] °C Temperature of the water column by CTD TEMPCU01 °C Not banked by BODC. Data are un-calibrated. Used as source for TEMPCC01.
Voltage 2 Un-adjusted volts Voltage from CTD PAR sensor LVLTLD01 Un-adjusted volts Not banked by BODC. These data are used as source data for the calculation of IRRDUV01.
Voltage 3 Un-adjusted volts Beam transmissometer voltage TVLTCR01 Un-adjusted volts Not banked by BODC. These data are used as source data for the calculation of ATTNMR01
Voltage 4 Un-adjusted volts Voltage from CTD SCUFA Turner fluorometer. FVLTWS01 Un-adjusted volts -
Voltage 6 Un-adjusted volts LISST scatterometer voltage output NVLTLS01 Un-adjusted volts -
Voltage 7 Un-adjusted volts LISST transmissometer voltage output TVLTZR01 Un-adjusted volts -
- - Potential temperature of water body POTMCV01 °C Generated by BODC using UNESCO Report 38 (1981) algorithm with parameters PSALCC01 and TEMPCC01.
- - Sigma-theta SIGTPR01 Kg m-3 Generated by BODC using the Fofonoff and Millard (1982) algorithm
- - PAR IRRDUV01 µE m-2s-1 Generated by BODC from calibration of LVLTLD01
- - Beam Attenuation ATTNMR01 m-1 Generated by BODC from calibration of TVLTCR01
- - Temperature TEMPCC01 °C Generated by BODC from calibration of TEMPCU01
- - Oxygen saturation OXYSBB01 % Generated by BODC durinf transfer using the Benson and Krause (1984) algorithm.

References

Benson, B.B. and Krause, D., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnology and Oceanography., 29(3), 620-632

Fofonoff, N.P. and Millard, R.C., 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No. 44, 53pp.

UNESCO, 1981. Background papers and supporting data on the International Equation of State of Seawater 1980. UNESCO Technical Papers in Marine Science No. 38, 192pp

Screening

Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. Downcasts and upcasts were differentiated and the limits manually flagged. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

Banking

Once quality control screening was complete, CTD downcasts for all casts were binned against pressure at 0.5 dbar increments. During binning, BODC exclude flagged data and generate interpolated values to fill in gaps in the increment sequence, where necessary. Finally, the CTD downcasts were banked.

Calibrations

Salinity

Only 2 independent salinity samples were collected during the cruise. This does not provide a large enough population to enable a direct calibration of the CTD salinity values. The calibration equation for cruise PD35_06 (calibrated salinity = CTD salinity * 1.0623 - 1.9758) was considered as an alternative. In order to determine whether this calibration could be applied to the data, the mean salinity offset (independent salinity - CTD salinity) for PD37_06 was compared with that from cruise PD35_06. The mean offset for PD37_06 is -0.0186 with a standard deviation of 0.0199. This compares to a mean offset for PD35_06 of 0.0822 with a standard deviation of 0.0564. From these statistics and the small population of independent samples, it cannot be said with confidence that the calibration for PD35_06 is a suitable alternative and the user should exercise caution if applying it to the data. Because of the lack of a suitable calibration, uncalibrated salinity has been supplied.

Temperature

Two independent temperature values were obtained during the cruise. This does not provide a large enough population to enable a direct comparison against pressure and CTD temperature. The mean offset (independent temperature - CTD temperature) was calculated as -0.00415 with a standard deviation of 0.0009, compared to a mean offset of -0.00345 and standard deviation of 0.0048 for cruise PD35_06. These offsets are very similar and neither are significantly different from zero at 95% confidence. Therefore, there was no adjustment to the CTD temperature resulting from the application of manufacturer's coefficients during initial processing.

Pressure

There were no casts where the CTD pressure was logging in air. No adjustments were made to the values resulting from application of manufacturer's coefficients during the intial processing.

Beam attenuation

Coefficients M and B were calculated, allowing calibration of the transmissometer with air readings taken during the cruise. M and B are calculated according to SBE Application Note No. 7:

M = (Tw/W0)*(A0-Y0)/(A1-Y1)
B= -M*Y1

Where Tw is the percent transmission for pure water for the instrument (92.98%); W0 is the voltage output in pure water (4.649 volts); A0 is the manufacturer's air voltage (4.661 volts); Y0 is the manufacturer's blocked path voltage (0.000 volts); A1 is the cruise maximum air voltage (4.553 volts); Y1 is the current blocked path voltage (0.0000 volts). For this cruise, M and B were calculated to be 20.4744 and 0, respectively.

M and B are then inserted into the following equations (from SBE Application Note No. 7) to obtain calibrated beam attenuation:

Light transmission [%] = (M * voltage output) + B
Beam attenuation coefficient c = - (1/z) * ln (light transmission [decimal])

Where M and B are the calibration coefficients, z is the transmissometer path length (0.2m), light transmission[decimal] is light transmission [%] divided by 100, c = beam attenuation (m-1)

LISST transmission and scattering

The data are currently uncalibrated. However, the voltages can be calibrated to give optical transmission, beam attenuation, total volume concentration and Sauter mean diameter according to the following manufacturer's constants and calculations:

Optical Transmission = b = (VT-VToff)/(VTO-VToff)
Beam attenuation = -ln(b)/0.025 - units are metres-1, assumes 25mm path
Total volume concentration = TV = cal*[((VS-VSoff)/b)-(VSO-VSoff)] - units are µl l-1
Sauter mean diameter = SMD = a*[TV/(-ln(b)] - units are µm

Where cal = total volume concentration calibration constant = 160, a = Sauter mean diameter calibration constant = 0.09, VSO = clearwater scattering output = 0.150V (see note below), VTO = clear water transmission output = 3.215V (see note below), VSoff = scattering output offset = 0.10V, VToff = transmission output offset = 0.10V. Measured outputs are scattering = VS and transmission = VT.

N.B. The clear water values quoted above are supplied by the manufacturer. Ideally these should be replaced by values determined by the LISST calibration cast, during which the instrument is placed in a tank of clean water. However, there is suspicion that these values may not be accurate. Instrument degradation would be expected to produce a gradual decrease in the transmission value coupled with an increase in the scattering values. This is not the case and there are abnormally high values for some cruises. Therefore, manufacturer's values have been quoted along with values measured by the instrument during previous cruises. Users are advised to use their own discretion in deciding which coefficients to apply.

Date Cruise VT0 VS0
24/02/2004 PD06_04 3.292 0.442
02/03/2004 PD07_04 3.266 0.447
29/03/2004 PD11_04 3.357 0.447
10/05/2004 PD18_04 3.867 0.867
20/07/2004 PD29_04 3.501 0.468
10/08/2004 PD32_04 3.730 0.701
28/10/2004 PD48_04 3.372 0.459
14/12/2004 PD52_04 3.330 0.428
30/01/2005 PD02_05/PD03_05 3.319 0.469
28/02/2005 PD07_05 3.280 0.465
05/04/2005 PD11_05 3.299 0.455
10/05/2005 PD18_05 3.365 0.460
14/06/2005 PD21_05 3.371 0.479
13/07/2005 PD25_05 3.415 0.486
16/08/2005 PD30_05 3.171 0.463
14/09/2005 PD34_05 3.156 0.471
26/10/2005 PD41_05 3.145 0.442
13/12/2005 PD48_05 2.957 0.463
05/02/2006 PD04_06/PD05_06 3.071 0.523
05/03/2006 PD09_06 3.156 0.611
04/04/2006 PD12_06 2.969 0.447
08/05/2006 PD16_06 2.904 0.446
12/12/2006 PD37_06 2.723 0.156

PAR

The LI-COR LI-192SA sensor number 33 was calibrated from raw voltages using the CEFAS supplied equation:

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, 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

Cruise

Cruise Name PD37/06
Departure Date 2006-12-14
Arrival Date 2006-12-15
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 NameCOA
CategoryOffshore area
Latitude53° 31.51' N
Longitude3° 23.00' W
Water depth below MSL26.0 m

Liverpool Bay Coastal Observatory Mooring Site A (COA/Site 1/Site 9)

This station is the main mooring site for the Proudman Oceanographic Laboratory (POL) Liverpool Bay Coastal Observatory and was first occupied in 2002. It is also known both as Coastal Observatory Site 1 and Site 9. POL perform two main types of activities at this station: they deploy moorings; and in addition, they take CTD profiles during each site visit. The station lies within a box of mean water depth 22.5 m with the following co-ordinates:

Box Corner Latitude (+ve North) Longitude (+ve East)
North-west corner 53.54097 -3.42958
South-east corner 53.50945 -3.33714

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

2011

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, OBS, OXY 1117 for January cruise. Other frame IDs not available at this time. January - September
SmartBuoy CTD x 2, AC-S, CT x 2, FL x 3, OBS x 2, PAR x 2, WMS, NAS, OXY, T x 2 1116 for January cruise. Other frame IDs not available at this time. January - September
SparBuoy AC-S, FL, CTD x 2, T Frame ID not available at this time. September

2010

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, ADV, OBS 1086, 1090, 1094, 1098, 1102, 1106, 1109 January - December
SmartBuoy CT x 2, FL x 2, OBS, PAR x 2, WMS, NAS, CTD, OXY, BD, T 1085, 1089, 1093, 1097, 1101, 1105, 1108, 1112 January - December

2009

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, ADV, OBS 1055, 1062, 1067, 1071, 1074, 1078, 1082 January - December
SmartBuoy CT x 2, FL x 2, OBS, PAR x 2, WMS, NAS, CTD, OXY, BD, T 1054, 1061, 1066, 1070, 1073, 1077, 1081 January - December

2008

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, ADV, OBS 1024, 1028, 1032, 1036, 1041, 1044, 1047, 1051 January - December
SmartBuoy CT x 2, FL x 2, OBS, PAR x 2, WMS, NAS, CTD, OXY, BD, T LB1_047/1023, LB1_048/1027, LB1_049/1031, LB1_050/1035, 1040, 1043, LB1_053/1050 January - December

2007

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, ADV, OBS 990, 997, 1001, 1005, 1010, 1014, 1017, 1021 January - December
SmartBuoy CT x 2, FL x 2, OBS, PAR x 2, WMS, NAS, CTD, OXY, BD, T LB1_039/989, LB1_040/996, LB1_041/1000, LB1_042/1004, LB1_043/1009, LB1_044/1013, LB1_045/1016, LB1_046/1020 January - December

2006

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CTD, ADV, OBS 951, 962, 966, 970, 974, 978, 982, 986 January - December
SmartBuoy CT x 2, FL x 2, OBS, PAR x 2, WMS, NAS, CTD, OXY, BD 958, 961, 965, 969, 973, 977, LB1_037/981, LB1_038/985 January - December

2005

Rig Type Typical Instruments Rig IDs Comment
Frame ADCP, CT 913, 914, 921, 925, 929, 933, 938, 942, 945, 949 January - December
SmartBuoy CT, FL, OBS, PAR, WMS, NAS, OXY 912, 920, 924, 928, 932, 937, LB1_028/941, LB1_029/944, LB1_030/948 January - December
Frame with telemetry buoy ADCP 914 March - April

2004

Rig Type Typical Instruments Rig IDs Comment
Frame BPR, ADCP, TR, CT 890, 892, 893, 896, 898, 900, 902, 904, 907, 908, 910, 911 January - December
SmartBuoy CT, FL, OBS, PAR, WMS, NAS 889, 891, 895, 897, 899, 901, 903, 906, 909 January - December
Frame with telemetry buoy ADCP 893, 908, 911 April - May, October - December

2003

Rig Type Instruments Rig IDs Comment
Frame BPR, ADCP, TR, CT 861, 864, 866, 869, 872, 878, 880, 883, 885, 887, 888 January - December
SmartBuoy CT, FL, OBS, PAR, WMS, NAS 863, 865, 867, 870, 871, 877, 879, 882, 884, 886 January - December

2002

Rig Type Instruments Rig IDs Comment
Frame BPR, ADCP, TR, CT 851, 854, 856, 858 August - December
Line mooring CT x 3 853, 855 August - November
SmartBuoy CT, FL, OBS, PAR, WMS, NAS 857, 860 November - December

2001

Rig Type Instruments Rig IDs Comment
Frame ADCP, OBS 838, 839, 840, 841, 843, 844, 845, 846, 848, 849 September

CTD Sampling History

Year Number of Cruises Total Casts per year
2011 6 116 including a 46 cast tidal cycle from 2011-04-18 to 2011-04-19 and a 51 cast tidal cycle station from 2011-07-27 to 2011-07-28
2010 7 69 including a 52 cast tidal cycle station from 2010-04-28 to 2010-04-29
2009 7 21
2008 9 75 including a 54 cast tidal cycle station from 2008-05-13 to 2008-05-14
2007 8 71 including a 51 cast tidal cycle station from 2007-05-15 to 2007-05-16
2006 9 72 including a 53 cast tidal cycle station from 2006-05-09 to 2006-05-10
2005 9 41 including a 22 cast tidal cycle station from 2005-04-05 to 2005-04-06
2004 9 77 including a 54 cast tidal cycle station from 2004-05-11 to 2004-05-12
2003 10 28
2002 4 13

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

AC-S = Absorption and attenuation spectrophotometer
ADCP = Acoustic Doppler Current Profiler
ADV = Acoustic Doppler Velocimeter
BD = Bacterial degradation experiment
BPR = Bottom Pressure Recorder
CT = Conductivity and temperature logger
CTD = Conductivity, temperature, depth sensor
FL = Fluorometer
NAS = in-situ nutrient analyser
OBS = Optical Backscatter Turbidity meter
OXY = Oxygen sensor
PAR = PAR sensor
T = Temperature logger
TR = Transmissometer
WMS = Automatic water sampler

Other Series linked to this Fixed Station for this cruise - 747057 747162 747266 747334 747395 747451 747499 747506 752951 753026 753118 1003646

Other Cruises linked to this Fixed Station (with the number of series) - PD01/08 (16) PD02/03 (4) PD02/05 (3) PD02/07 (14) PD02/09B (16) PD02/10 (9) PD05/10 (10) PD06/07 (15) PD07/08 (14) PD09/06 (11) PD09/07 (63) PD09/08 (15) PD10/03 (3) PD10/10 (8) PD11/05 (1) PD11/11 (48) PD12/05 (2) PD12/09 (10) PD13/07 (13) PD14/08 (67) PD16/06 (8) PD16/07 (14) PD17/03 (4) PD17/10 (9) PD18/04 (5) PD18/05 (3) PD18/09 (11) PD19/08 (2) PD20/02 (5) PD20/06 (8) PD20/07 (16) PD21/05 (3) PD21/10 (9) PD22/04 (5) PD22/06 (8) PD23/03A (4) PD23/07 (15) PD23/08 (12) PD24/02 (1) PD24/09 (11) PD25/03B (4) PD25/05 (3) PD25/06 (8) PD25/11 (4) PD27/07 (16) PD29/04 (4) PD29/06 (8) PD29/08 (13) PD29/10 (11) PD30/05 (2) PD31/02 (4) PD31/03 (4) PD32/04 (4) PD33/08 (4) PD33/09 (10) PD34/03 (4) PD34/05 (9) PD35/02 (4) PD35/06 (13) PD36/10 (10) PD37/06 (12) PD37/08 (17) PD38/03 (5) PD38/04 (4) PD38/09 (10) PD41/05 (10) PD43/11 (3) PD47/09 (9) PD48/05 (10) PD49/10 (7)

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