Metadata Report for BODC Series Reference Number 974278


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Chelsea Technologies Group Aquatracka fluorometer  fluorometers
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Tritech PA-200 Altimeter  altimeters
WETLabs C-Star transmissometer  transmissometers
Biospherical QCD-905L underwater PAR sensor  radiometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr Hugh Venables
Originating Organization British Antarctic Survey
Processing Status banked
Project(s) DISCOVERY 2010
 

Data Identifiers

Originator's Identifier JR200_CTD023_2DB
BODC Series Reference 974278
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-03-25 16:22
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 57.13990 S ( 57° 8.4' S )
Longitude 42.43370 W ( 42° 26.0' W )
Positional Uncertainty 0.01 to 0.05 n.miles
Minimum Sensor Depth 0.99 m
Maximum Sensor Depth 3637.1 m
Minimum Sensor Height 96.53 m
Maximum Sensor Height 3732.65 m
Sea Floor Depth 3733.64 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 Chart reference - Depth extracted from available chart
 

Parameters

BODC CODE Rank Units Short Title Title
ACYCAA01 1 Dimensionless Record_No Sequence number
AHSFZZ01 1 Metres Height Height above bed in the water body
CNDCST01 1 Siemens per metre CTDCond Electrical conductivity of the water body by CTD
CNDCST02 1 Siemens per metre CTDCond2 Electrical conductivity of the water body by CTD (sensor 2)
CPHLPR01 1 Milligrams per cubic metre chl-a_water_ISfluor Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer
DOXYSU01 1 Micromoles per litre WC_dissO2_uncalib Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by Sea-Bird SBE 43 sensor and no calibration against sample data
IRRDUV01 1 MicroEinsteins per square metre per second SubsurVPAR Downwelling vector irradiance as photons (PAR wavelengths) in the water body by cosine-collector radiometer
POPTDR01 1 Percent Trans_Red_25cm Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer
PRESPR01 1 Decibars Pres_Z Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALCC01 1 Dimensionless P_sal_CTD_calib Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements
PSALCC02 1 Dimensionless P_sal_CTD_calib2 Practical salinity of the water body by CTD (second sensor) and computation using UNESCO 1983 algorithm and calibration against independent measurements
TEMPCC01 1 Degrees Celsius Cal_CTD_Temp Temperature of the water body by CTD and verification against independent measurements
TEMPCC02 1 Degrees Celsius Cal_CTD_Temp2 Temperature of the water body by CTD and verification against independent measurements
 

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

Data Quality Report

Series ref. number (CTD cast ID) Channel Comment
974070 (JR200_CTD003) AHSFZZ01 Spike at 7m flagged (M) suspicious
974082 (JR200_CTD004) AHSFZZ01 Spike at 240m flagged (M) suspicious
974174 (JR200_CTD013) CPHLPR01 Spike at 1900m flagged (M) suspicious
974278 (JR200_CTD023) CNDCST01, TEMPCC01, PSALCC01 Entire cast flagged (M) suspicious, noted in cruise report that primary sensors failed to work on this cast. Data is messy.
974291 (JR200_CTD024) CNDCST02, TEMPCC02, PSALCC02 Entire cast flagged (M) suspicious, noted in cruise report that secondary sensors failed to work on this cast. Data is messy.
974358 (JR200_CTD031) All channels Cycles 109-131m automatically flagged null (N)
DOXYSU01 Spike at 103m flagged (M) suspicious
974414 (JR200_CTD036) AHSFZZ01 Messy patch at 180m flagged (M) suspicious
974438 (JR200_CTD038) CNDCST01, PSALCC01 Spike at 560m flagged (M) suspicious
974451 (JR200_CTD039) AHSFZZ01 Spike at 9m flagged (M) suspicious
974487 (JR200_CTD042) AHSFZZ01 Spike at 73m flagged (M) suspicious

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

Instrumentation

During the BAS core cruise JR20090308 (JR200), a full size SBE 24 carousel water sampler, holding 12 bottles, connected to an SBE 9 plus CTD and a SBE 11 plus deck unit was used to collect vertical profiles of the water column. The deck unit provides power, real time data acquisition and control. The underwater SBE 9 plus unit featured dual temperature (SBE 3 plus) and conductivity (SBE 4) sensors, and a Paroscientific pressure sensor. A temperature-conductivity (TC) duct and a pump-controlled flow system ensured that the flow through the TC duct is constant to minimize salinity spiking.

In addition, a Tritech PA200 Digital Precision Altimeter , a Chelsea Aquatracker III fluorometer , a SBE 43 oxygen sensor , a Biospherical QCD905L photosynthetically active radiation (PAR) sensor and a Wet-Labs C-Star Transmissometer (6000 m; red wavelength; 25cm pathlength) were attached to the carousel.

The CTD data were logged via the deck unit to a 1.4GHz P4 PC, running Seasave Win32 version 5.7b (Sea-Bird Electronics Inc.). The data rate of recorded data for the CTD was 24 Hz.

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 .

Aquatracka fluorometer

The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.

The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.

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

Biospherical Instruments Log Quantum Cosine Irradiance Sensor QCD-905L

The QCD-905L is a submersible radiometer designed to measure irradiance over Photosynthetically Active Radiation (PAR) wavelengths (400-700 nm). It features a cosine directional response when fully immersed in water.

The sensor is a blue-enhanced high stability silicon photovoltaic detector with dielectric and absorbing glass filter assembly, and produces a logarithmic output. Normal output range is -1 to 6 volts with 1 volt per decade. Typically, the instrument outputs 5 volts for full sunlight and has a minimum output of 0.001% full sunlight, where typical noon solar irradiance is 1.5 to 2 x 10 17 quanta cm -2 s -1 . The instrument can be calibrated with constants for µE cm -2 s -1 or quanta cm -2 s -1 .

The QCD-905L can be coupled to a fixed range data acquisition system like a CTD (Conductivity-Temperature-Depth) profiler or current meter. It has an aluminium and PET housing, and a depth rating of 7000 m.

Specifications

Wavelength 400 to 700 nm
Output range -1 to 6 V, with 1 V decade -1
Operating temperature -2 to 35°C
Depth range 0 - 7000 m

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

Tritech Digital Precision Altimeter PA200

This altimeter is a sonar ranging device that gives the height above the sea bed when mounted vertically. When mounted in any other attitude the sensor provides a subsea distance. It can be configured to operate on its own or under control from an external unit and can be supplied with simultaneous analogue and digital outputs, allowing them to interface to PC devices, data loggers, telemetry systems and multiplexers.

These instruments can be supplied with different housings, stainless steel, plastic and aluminum, which will limit the depth rating. There are three models available: the PA200-20S, PA200-10L and the PA500-6S, whose transducer options differ slightly.

Specifications

Transducer options PA200-20S P200-10L PA500-6S
Frequency (kHz) 200 200 500
Beamwidth (°) 20 Conical 10 included conical beam 6 Conical
Operating range

1 to 100 m

0.7 to 50 m

-

0.3 to 50 m

0.1 to 10 m

Common specifications are presented below

Digital resolution 1 mm
Analogue resolution 0.25% of range
Depth rating 700 , 2000, 4000 and 6800 m
Operating temperature -10 to 40°C

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

WETLabs C-Star transmissometer

This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.

Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.

This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.

Specifications

Pathlength 10 or 25 cm
Wavelength 370, 470, 530 or 660 nm
Bandwidth

~ 20 nm for wavelengths of 470, 530 and 660 nm

~ 10 to 12 nm for a wavelength of 370 nm

Temperature error 0.02 % full scale °C -1
Temperature range 0 to 30°C
Rated depth

600 m (plastic housing)

6000 m (aluminum housing)

Further details are available in the manufacturer's specification sheet or user guide .

BODC Processing

The data arrived at BODC in NetCDF (m*) format representing the CTD data collected during BAS core cruise JR20090308 (JR200). These were reformatted to the internal QXF format using BODC established procedures. The following table shows how the variables within the originator's data files were mapped to the BODC parameter codes:

Originator's Variable Units Description BODC Parameter Code Units Comments
press db Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level PRESPR01 db Data originator applied pressure offset to data
temp °C (ITS-90) Temperature of the water body by CTD and verification against independent measurements TEMPCC01 °C Data were collected against bottle samples before submission to BODC
temp2 °C (ITS-90) Temperature of the water body by CTD and verification against independent measurements TEMPCC02 °C Data were calibrated against bottle samples before submission to BODC
cond µS cm -1 Electrical conductivity of the water body by CTD CNDCST01 S m -1 original data divided by 10 during BODC transfer
cond2 µS cm -1 Electrical conductivity of the water body by CTD CNDCST02 S m -1 original data divided by 10 during BODC transfer
psal pss_78 Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements PSALCC01 dimensionless Data were calibrated against bottle samples before submission to BODC
psal2 pss-78 Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements PSALCC02 dimensionless Data were calibrated against bottle samples before submission to BODC
altimeter m Height above bed in the water body AHSFZZ01 m n/a
fluor µg l -1 Concentration of chlorophyll-a (chl-a) per unit volume of the water body [particulate phase] by in-situ chlorophyll fluorometer CPHLPR01 mg m -3 no conversion necessary, units analogous with each other
oxy ml l -1 Concentration of oxygen (O 2 ) per unit volume of the water body [dissolved phase] by Sea-Bird SBE 43 sensor and no calibration against sample data DOXYSU01 µmol l -1 original data x44.66 during BODC transfer
par µmol m -2 s -1 Downwelling vector irradiance as photons (PAR wavelengths) in the water body by cosine-collector radiometer IRRDUV01 µE m -2 s -1 no conversion necessary, units analogous with each other
trans % Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer POPTDR01 % -

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.

Originator's Data Processing

Sampling Strategy

A total of 50 CTD casts were completed during cruise JR20090308 (JR200) which included one test station, eight biological stations, thirty physics station plus additional CTD casts for testing and prior to the acoustics calibration. At each of the biological stations, at least three CTDs were carried out: one full depth CTD and two water sample CTDs to 400m and 2000m (or the seabed, if shallower than 2000m).

The general deployment procedure was to start data logging, deploy the CTD from the mid-ships gantry on a cable connected to the CTD through a conducting swivel, then stop the instrument at 10m wireout, where the CTD package was left for at least two minutes to allow the seawater-activated pumps to switch on and the sensors to equilibrate with ambient conditions.The pumps typically do not operate until 30-60 seconds after the CTD has been in the water. After a two minute soak, the package was raised to just below the surface and then continuously lowered to near bottom, with the Niskin bottles being closed during the upcast. The final CTD product was formed from the calibrated downcast data averaged to 2 db intervals.

Data Acquisition and CTD data processing

The CTD data were output to individual PStar files using the Seasave Win 32 version 5.28e module. The CTD data were then subsequently converted from binary to ascii and calibrated by running the Sea-Bird Electronics Inc. Data Processing software version 5.37b Data Conversion module.

The following routine from Sea-Bird Electronics Inc. Data Processing software version 5.37b was applied:

Further processing of CTD data was carried out in Matlab using existing programs, predominantly written by Mike Meredith and Karen Heywood, with modifications by others. These scripts included functions to remove the 10m soak prior to the CTD cast, remove large spikes in all channels, interpolate missing data, apply derived offsets to the CTD conductivities and calculate salinity, potential temperature and potential densities. For full details of all calculations applied to this data set please see the JR20090308 (JR200) cruise report .


Project Information

DISCOVERY 2010

DISCOVERY 2010 will investigate and describe the response of an ocean ecosystem to climate variability, climate change and commercial exploitation. The programme builds on past studies by BAS on the detailed nature of the South Georgia marine ecosystem and its links with the large-scale physical and biological behaviour of the Southern Ocean.

The aim is to identify, quantify and model key interactions and processes on scales that range from microscopic life forms to higher predators (penguins, albatrosses, seals and whales), and from the local to the circumpolar.

Objectives

Assess the links between the status of local marine food webs and variability and change in the Southern Ocean. Develop a linked set of ecosystem models applying relevant marine physics and biology over scales from the local to that of the entire Southern Ocean.

Relevance to Global Science

Ocean ecosystems play a crucial role in maintaining biodiversity, in depositing carbon into the deep ocean, and as a source of protein for humans. However, fishing and climate change are having significant and often detrimental effects. To predict the future state of ocean ecosystems we must develop computer models capable of simulating biological and physical processes on a range of scales from the local to an entire ocean. Developing such predictive models is crucial to the sustainable management of world fisheries and requires integrated analyses of the way whole ecosystems work. DISCOVERY 2010 aims to take this work forward and at the same time help manage the South Georgia and South Sandwich Islands maritime zone. We will do this through providing information on the state of the ecosystem to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the international body that manages sustainable fishing in the Southern Ocean.

Delivering the Results

DISCOVERY 2010 will undertake an integrated programme of shipboard and land-based field studies of the marine food web, combined with modelling. We will pay particular attention to critical phases in the life cycles of key species, and to examining interactive effects in food webs. Interacting biological and physical processes will be modelled across a range of spatial scales to significantly improve our representation of the ocean ecosystem, upon which sustainable management and the prediction of future climate change can be based. DISCOVERY 2010 will link to BIOFLAME, ACES, and COMPLEXITY, two international programmes, and to a collaborative programme with the University of East Anglia on the role of the Southern Ocean in the global carbon cycle.

Component Projects


Data Activity or Cruise Information

Cruise

Cruise Name JR20090312 (JR200, JR200A, JR208)
Departure Date 2009-03-11
Arrival Date 2009-04-18
Principal Scientist(s)Rebecca Korb (British Antarctic Survey)
Ship RRS James Clark Ross

Complete Cruise Metadata Report is available here


Fixed Station Information


No Fixed Station Information held for the Series


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