Metadata Report for BODC Series Reference Number 1623562

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

UK Ocean Acidification Underway Atmospheric and Seawater pCO₂, Cruise D366,PML pCO₂ Data Quality Report

There are no known issues with these data.

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

LI-COR 840 and LI-COR 840A CO₂/H₂O Gas Analysers

General Information

The LI-840 and 840A CO₂/H₂O analysers are simple, low maintenance gas analysers designed for continuous monitoring applications. They are absolute, non-dispersive infrared (NDIR) gas analysers based upon a field proven single path, dual wavelength and thermostatically controlled infrared detection system. They can be used in a wide range of environmental conditions.

Key Features

• Easy integration into monitoring systems.
• Wide Measurement Range: 0-20,000 ppm (0-2%) for CO2 and 0-60 mmol/mol for H2O (dry air to 36°C dew point).
• Wide Operating Temperature: -20° to +45°C.
• Low Power Consumption: Less than 4W after power-up.
• Low Noise: Less than 1 ppm at 370 ppm for CO2, less than 0.01 mmol/mol at 10 mmol/mol for H2O with 1 second signal averaging.
• Flow Rate: Maximum of 1 liter/minute.
• Real-Time, Corrected Readings: On-board sensors measure and correct for changes in cell temperature and pressure.
• CO2 concentrations are corrected for band-broadening due to water vapor.
• User-Cleanable Optics: The optical bench can be easily cleaned by the user. This reduces down-time from contamination and eliminates the need for factory recalibration.
• Estimated 2+ year source life in continuous operation. The source is field-replaceable without factory calibration.

Specification

CO₂

H₂O

⁽¹⁾Zero Drift is the change with temperature at 0 concentration.

⁽²⁾Span Drift is the residual error after re-zeroing following a temperature change.

⁽³⁾Total Drift is the change with temperature without re-zeroing or re-spanning.

Other Specifications

More information may be found in the LI-840 manufacturer's manual or the LI-840A manufacturer's brochure.

Vaisala Analog Barometers Models PTB100 (A), (B) and PTB101 (B), (C)

The PTB 100 series analog barometers are designed both for accurate barometric measurements at room temperature and for general environmental pressure monitoring over a wide temperature range. The long-term stability of the barometer minimizes the need for field adjustment in many applications.

Physical Specifications

The barometers use the BAROCAP^* silicon capacitive absolute pressure sensor developed by Vaisala for barometric pressure measurements. The BAROCAP^* sensor combines the elasticity characteristics and mechanical stability of a single-crystal silicon with the proven capacitive detection principle.

Sensor Specifications

^* BAROCAP is a registered trademark of Vaisala

SeaBird MicroTSG Thermosalinograph SBE 45

The SBE45 MicroTSG is an externally powered instrument designed for shipboard measurement of temperature and conductivity of pumped near-surface water samples. The instrument can also compute salinity and sound velocity internally.

The MicroTSG comprises a platinum-electrode glass conductivity cell and a stable, pressure-protected thermistor temperature sensor. It also contains an RS-232 port for appending the output of a remote temperature sensor, allowing for direct measurement of sea surface temperature.

The instrument can operate in Polled, Autonomous and Serial Line Sync sampling modes:

• Polled sampling: the instrument takes one sample on command
• Autonomous sampling: the instrument samples at preprogrammed intervals and does not enter quiescence (sleep) state between samples
• Serial Line Sync: a pulse on the serial line causes the instrument to wake up, sample and re-enter quiescent state automatically

Specifications

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

UK Ocean Acidification Underway Atmospheric and Seawater pCO₂, Cruise D366,PML pCO₂ Processing Document

Originator's Processing Notes

Methodology

An automated pCO2 measurement system (Live pCO2) (Hardman-Mountford et al., 2008) was installed on the UK NERC research vessels (RRS Discovery). The system used a vented-shower-head equilibrator and an infrared detection (LI-COR, LI-840). In order to maintain atmospheric pressure in the equilibrator headspace, the latter was vented to a second equilibrator, which in turn was vented to the atmosphere via a 2 m coil of stainless steel tubing (1.5 mm internal diameter). The equilibrator was fitted with 2 platinum resistance thermometers and a water-jacket supplied with seawater from the underway system. The average warming between the ship's underway seawater intake and the equilibrator was 0.45±0.05°C. Atmospheric measurements were taken from an intake located on the foremast. Both the equilibrator and atmospheric gas streams were dried in a Peltier cooler (-20°C). Measurements were referenced against standard CO₂ in synthetic air mixtures (0, 251.3 and 446.9 µmol CO2?mol-1) which were referenced against certified US National Oceanic and Atmospheric Administration (NOAA) standards (244.94 ppmv and 444.37 ppmv CO₂ in air) in the laboratory prior to deployment.

Data Processing - Equations

The LivepCO₂ instrument measures CO₂ dry mole fraction (xCO_{2 dry}). This is used to compute pCO₂ (pCO_{2 equ}) at the equilibrator temperature (T_equ) and pressure (P_equ):

pCO_{2 equ} = xCO_{2 dry} * (P_equ - pH₂O)

pH₂O is the water vapour pressure at T_equ (Weiss and Price, 1980):

pH₂O = exp(24.5443 - 67.4509 * (100/T_equ) - 4.8489 * ln(T_equ/100) -0.000544 * Salinity)

Finally, pCO₂ at sea surface temperature is calculated according to the following equation (Takahashi et al., 1993):

pCO_{2 SST} = pCO_{2 equ} * exp(0.0423 * (SST - T_equ))

Corresponding atmospheric pCO₂ measurements are interpolated from measurements immediately before and after xCO₂ dry measurements (circa 10 minutes).

BODC Processing Notes

Data were submitted to BODC as an Excel .xlsx file containing metadata and data on one sheet. This was subsequently archived alongside two .csv files containing the data and metadata resepctively. The data were then transferred to the BODC format and loaded to the database. Parameter codes defined in the BODC dictionary were assigned to the variables as shown in the table below:

Screening

The data were visualised using the bespoke BODC software EDSERPLO with suspicious values flagged where appropriate.

There was a period of time where the latitude and longitude appeared to be stationary for a large period of time, from 26/06/2011 10:50:00 to 26/06/2011 20:09:00. These position values were all flagged as suspect, 'M'. The cruise underway data is available upon request.

A spike was flagged suspect, 'M', in the pressure channels CAPHZZ01 and PRES00EQ. In addition to this flag a few values were flagged as suspect, 'M', in the salinity channel, PSALZZXX.

In the pCO₂ channels, XCO2WBDY and PCO2XXXX, a few data were flagged suspect, 'M', where it looked like the instrument was adjusting to being turned and/or cleaned.

References

Hardman-Mountford, N.J., Moore, G., Bakker, D.C.E., Watson, A.J., Schuster, U., Barciela, R., Hines, A., Moncoiffe, G., Brown, J., Dye, S., Blackford, J., Somerfield, P.J., Holt, J., Hydes, D.J., Aiken, J., 2008. An operational monitoring system to provide indicators of CO2-related variables in the ocean. ICES J. Mar. Sci. 65, 1498-1503.

Takahashi, T., J. Olafsson, J.G. Goddard, D.W. Chipman, S.C. Sutherland (1993) Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: a comparative study. Global Biogeochemical Cycles 7, 843-878.

Weiss, R.F., Price, B.A., 1980. Nitrous-Oxide Solubility in Water and Seawater. Marine Chemistry 8, 347-359.

UK Ocean Acidification Underway Atmospheric and Seawater pCO₂, Cruise D366,PML pCO₂ Instrumentation Document

The following instruments and the parameters they measured are given below:

Project Information

UKOARP Theme B: Ocean acidification impacts on sea surface biology, biogeochemistry and climate

The overall aim of this theme is to obtain a quantitative understanding of the impact of ocean acidification (OA) on the surface ocean biology and ecosystem and on the role of the surface ocean within the overall Earth System.

The aims of the theme are:

• To ascertain the impact of OA on planktonic organisms (in terms of physiological impacts, morphology, population abundances and community composition).
• To quantify the impacts of OA on biogeochemical processes affecting the ocean carbon cycle (both directly and indirectly, such as via availability of bio-limiting nutrients).
• To quantify the impacts of OA on the air-sea flux of climate active gases (DMS and N₂O in particular).

The main consortium activities will consist of in-situ measurements on three dedicated cruises, as well as on-deck bioassay experiments probing the response of the in-situ community to elevated CO₂. Most of the planned work will be carried out on the three cruises to locations with strong gradients in seawater carbon chemistry and pH; the Arctic Ocean, around the British Isles and the Southern Ocean.

Weblink: http://www.oceanacidification.org.uk/research_programme/surface_ocean.aspx

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: