Metadata Report for BODC Series Reference Number 1224444

• 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

UKOA Underway Atmospheric and Seawater pCO₂ Data Quality Report - JR271 (JR20120601)

The quality controlled data received by BODC has no known data quality issues.

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

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 PTB210 Digital Barometer

The basic specifications for this pressure sensor are as follows:

• Manufacturer: Vaisala
• Type: Silicon capacitive sensor
• Model: PTB210
• Range: 900 - 1100 hPa
• Output: 0-5VDC
• Total Accuracy (20°C): ±0.30hPa
• Operating temperature: -40 to +60 deg C
• Weight: 110g
• Certification Ingress Protection: IP65

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

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.

UKOA Underway Atmospheric and Seawater pCO₂ Instrumentation Document - JR271 (JR20120601)

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

UKOA Underway Atmospheric and Seawater pCO₂ Processing Document - JR271 (JR20120601)

Originator's Processing Notes

Methodology

Continuous measurements of the partial pressure of CO₂ (pCO₂) in surface water and marine air were made throughout the cruise by infrared detection on a LI-COR LI-840. The ship's seawater supply provided water for underway sampling from 5 m depth at the bow to the main lab. Temperature and salinity of the intake water were determined by the ship's sensors.

Seawater flowed through an equilibrator. Part of the water went to waste via a bypass. The equilibrator was operated at a flow rate of 0.8 to 1.8 l min^-1. The water flow rate was recorded twice a day.

The system, comprising a shower-head equilibrator, infrared gas analyzer (LICOR, LI-840), processing and communication hardware, allows regular (20 min) sampling of seawater pCO₂ and atmospheric CO₂, referenced against standard gases (Hardman-Mountford et al., 2008). Standard gases used for the calibration, nominally 250 ppmv, 380 ppmv and 450 ppmv CO₂in air (BOC Ltd.), were separately 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.

The equilibrator headspace is vented to a second equilibrator, thereby allowing the former to draw seawater-equilibrated headspace from the latter if the pressure decreases ('vented system' configuration). The second equilibrator is vented to the atmosphere thereby maintaining pressure equilibrium. Inter-calibration tests showed agreement within 0.5 µatm between the new equilibrator Live pCO2 and similar systems.

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 separately. 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 variable as shown in the table below:

Screening

The data were screened using BODC in-house software, Edserplo.

One spike was flagged as suspect at cycle number 72 for parameter ACO2XXXX.

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.

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: