Metadata Report for BODC Series Reference Number 1044074


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Seapoint chlorophyll fluorometer  fluorometers
WETLabs C-Star transmissometer  transmissometers
Instrument Mounting lowered unmanned submersible
Originating Country New Zealand
Originator Prof Phil Boyd
Originating Organization NIWA, Centre for Chemical and Physical Oceanography, University of Otago
Processing Status banked
Project(s) GEOTRACES
 

Data Identifiers

Originator's Identifier U4830_1
BODC Series Reference 1044074
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2006-07-23 05:46
End Time (yyyy-mm-dd hh:mm) 2006-07-23 06:47
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 47.72300 S ( 47° 43.4' S )
Longitude 158.63699 E ( 158° 38.2' E )
Positional Uncertainty Unspecified
Minimum Sensor Depth 2.0 m
Maximum Sensor Depth 3048.0 m
Minimum Sensor Height 1901.0 m
Maximum Sensor Height 4947.0 m
Sea Floor Depth 4949.0 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 Short Title Title
ACYCAA01 1 Dimensionless Record_No Sequence number
DOXMZZXX 1 Micromoles per kilogram DissO2_Mass Concentration of oxygen {O2 CAS 7782-44-7} per unit mass of the water body [dissolved plus reactive particulate phase]
FVLTQSD1 1 Volts SD_AqVolt Instrument output standard deviation (voltage) by in-situ Aquatracka chlorophyll fluorometer
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 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

Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F

The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.

Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.

Specifications

Housing Plastic or titanium
Membrane

0.5 mil- fast response, typical for profile applications

1 mil- slower response, typical for moored applications

Depth rating

600 m (plastic) or 7000 m (titanium)

10500 m titanium housing available on request

Measurement range 120% of surface saturation
Initial accuracy 2% of saturation
Typical stability 0.5% per 1000 h

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

Instrument Descriptions TAN0609

CTD Unit and Auxiliary Sensors

Stainless Steel CTD

The CTD unit was a Sea-Bird 9/11 plus with dual temperature and conductivity sensors. All other instruments were attached to a Sea-Bird 32 12 or 24 bottle Carousel Water Sampler, equipped with Ocean Test Equipment Inc. Standard 10-litre external spring Niskin-type water-sampling bottles.

The table below lists available information about the various sensors.

Sensor Model Comments
Conductivity sensor SBE 4C Two sensors
Temperature sensor SBE 3 Two sensors
Dissolved oxygen SBE 43 -
Transmissometer Wetlabs Inc. C-Star 25cm path red beam transmissometer
Fluorometer Seapoint Sensors Inc. -

Trace Metal clean system

Samples were collected using acid-cleaned 5 L, Teflon coated, externally sprang, Nisken bottles attached to an autonomous rosette (Model 1018, General Oceanics, USA).

No sensors were attached to the rosette. The CTD system was deployed using a 12 mm diameter Spectra rope (Donaghys, New Zealand).

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 .

Seapoint Chlorophyll Fluorometer

The Seapoint Chlorophyll Fluorometer (SCF) is a low power instrument for in situ measurements of chlorophyll a. The SCF uses modulated blue LED lamps and a blue excitation filter to excite chlorophyll a. The fluorescent light emitted by the chlorophyll a passes through a red emission filter and is detected by a silicon photodiode. The low level signal is then processed using synchronous demodulation circuitry which generates an output voltage proportional to chlorophyll a concentration. The SCF may be operated with or without a pump.

Sensor specifications, current at August 2006, are given in the table below. More information can be found at the manufacturer's web site .

Sensor Specifications

Power requirements 8 - 20 VDC, 15 mA avg., 27 mA pk.
Output 0 - 5.0 VDC
Output Time Constant 0.1 sec.
Power-up transient period < 1 sec.
Excitation Wavelength 470 nm CWL, 30 nm FWHM
Emission Wavelength 685 nm CWL, 30 nm FWHM
Sensing Volume 340 mm 3
Minimum Detectable Level 0.02 µg l -1

  Gain Sensitivity, V µg -1 l -1 Range, µg l -1
Sensitivity/Range 30x
10x
3x
1x
1.0
0.33
0.1
0.033
5
15
50
150

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 TAN0609

Reformatting

The data arrived at BODC in 51 ASCII files which were reformatted to BODC internal QXF format (subset of NETcdf). Times were converted from NZST to GMT.

The following table shows how the variables within the ASCII files were mapped to appropriate BODC parameter codes:

Originator's Parameter Name Units Description BODC Parameter Code Units Comments
Pressure, Digiquartz dbar Pressure of water body on profiling pressure sensor PRESPR01 dbar -
Temperature [ITS-90] °C Temperature of water column by CTD TEMPCC01 °C -
Temperature [ITS-90] °C Temperature of water column by CTD TEMPCC02 °C Secondary temperature sensor
Salinity, Practical - Practical salinity of the water body by CTD PSALCC01 - Generated by Sea-Bird software from CTD temperature and conductivity data
Salinity, Practical - Practical salinity of the water body by CTD PSALCC02 - Generated by Sea-Bird software from CTD secondary temperature and conductivity data
Oxygen, SBE 43 µmol/Kg Dissolved oxygen concentration from SBE 43 sensor DOXMSDXX µmol/Kg -
Beam Transmission Percent Beam transmissometer from CTD sensor using a 25cm pathlength POPTDR01 Percent -
Fluorometer Volts Instrument output (voltage) by in-situ fluorometer FVLTZZ01 Volts -

Screening

Reformatted CTD data were visualised using the in-house graphical editor EDSERPLO. No data values were edited or deleted. Quality control flags were applied to data as necessary.

Banking

Once quality control screening was complete, CTD downcasts for all casts were loaded into BODC's National Oceanographic Database (NODB).

References

Fofonoff, NP and Millard, RC (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

Originator's Data Processing TAN0609

Sampling Strategy

A total of 71 CTD casts were completed during the cruise TAN0609. Both a stainless steel (51 casts) and a trace metal sampler (12 successful casts from a total of 20) were used.

Salinity and oxygen samples were collected to calibrate the CTD sensors. Salinity measurements were made on board using a Guildline Autosal 8400B salinometer.

Data Processing

No CTD data are available for the trace metal rosette sampler. All other CTD data was processed to NIWA Ocean CTD Facility (NOCF) level 2 processing specifications.

The raw data files were processed using SeaBird's software, SBE DataProcessing-Win32. The following routines were applied.
Datcnv - apply pre-cruise calibrations to convert each sensor output into physical units
Alignctd - advance SBE 43 voltage by 6 seconds relative to pressure. (Conductivity (x2) already advanced 0.073 seconds relative to tempeinture (x2) by SBE 11 plus CTD deck unit.)
Wildedit - for each of temperature (x2), conductivity (x2), pressure, dissolved oxygen, fluoresence and transmission, time series measurement in blocks of ten values. Compute mean and standard deviation of block, and temporarily exclude any values further than two standard deviations from mean. Recompute mean and standard deviation of block, and mark as bad any of original ten values further than twenty recomputed standard deviations from recomputed mean.
Filter - for each of condutivity (x2), zero-phase-shift low-pass filter of time-constant 0.03 seconds was applyied. For each of pressure, fluorescence, beam transmission, a zero-phase-shift low-pass filter of time-constant 0.15 seconds was applied.
Celltm - for each of condutivity (x2), applied a recursive filter with (dimensionless) amplitude 0.03 and time constant of 7 seconds to remove conductivity cell thermal mass effects.
Split - casts were split at the deepest point into down casts and up casts.
Derive - for both down cast and up cast, potential temperature (x2), salinity (x2)and dissolved oxygen were derived.
Binavg - for both down cast and up cast, all measurement were bin averaged in blocks of 0.5 seconds.
Ascii_out - for both down cast and up cast, one .asc file and one .hdr file was outputted.

Field Calibrations

After the initial CTD processing discrete independent salinity and oxygen samples, obtained from the CTD rosette, were used to calibrate the CTD sensor data.


Project Information

GEOTRACES

Introduction

GEOTRACES is an international programme sponsored by SCOR which aims to improve our understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes (TEIs) in the marine environment. The global field programme started in 2009 and will run for at least a decade. Before the official launch of GEOTRACES, fieldwork was carried out as part of the International Polar Year (IPY)(2007-2009) where 14 cruises were connected to GEOTRACES.

GEOTRACES is expected to become the largest programme to focus on the chemistry of the oceans and will improve our understanding of past, present and future distributions of TEIs and their relationships to important global processes.

This initiative was prompted by the increasing recognition that TEIs are playing a crucial role as regulators and recorders of important biogeochemical and physical processes that control the structure and productivity of marine ecosystems, the dispersion of contaminants in the marine environment, the level of greenhouse gases in the atmosphere, and global climate.

Scientific Objectives

GEOTRACES mission is: To identify processes and quantify fluxes that control the distribution of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.

Three overriding goals support the GEOTRACES mission

These goals will be pursued through complementary research strategies, including observations, experiments and modelling.

Fieldwork

The central component of GEOTRACES fieldwork will be a series of cruises spanning all Ocean basins see map below.

BODC image

Three types of cruise are required to meet the goals set out by GEOTRACES. These are

IPY-GEOTRACES

The IPY-GEOTRACES programme comprised of 14 research cruises on ships from 7 nations; Australia, Canada, France, Germany, New Zealand, Japan and Russia. The cruises will not be classified in the same way as the full GEOTRACES programme since the intercalibration protocols and data management protocols had not been established before the start of the IPY. But IPY-GEOTRACES data will still be quality controlled by GDAC and in the majority of cases verified versus Intercalibration standards or protocols.

Key parameters

The key parameters as set out by the GEOTRACES science plan are as follows: Fe, Al, Zn, Mn, Cd, Cu; 15N, 13C; 230Th, 231Pa; Pb isotopes, Nd isotopes; stored sample, particles, aerosols.

Weblink:

http://www.bodc.ac.uk/geotraces/
http://www.geotraces.org/


Data Activity or Cruise Information

Cruise

Cruise Name TAN0609 (GIPY1)
Departure Date 2006-07-12
Arrival Date 2006-08-05
Principal Scientist(s)Philip Boyd (NIWA, Centre for Chemical and Physical Oceanography, University of Otago)
Ship Tangaroa

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