Metadata Report for BODC Series Reference Number 1808764

• 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 (UKOA) RRS James Clark Ross Cruise JR20120601/JR271 Continuous pH Data Quality Report

Data were screened using in house visualisation software using the flow rate channel as a guide to the times when the underway flow was switched off, dropped low or was adjusted during the cruise. After the underway flow was swtiched back on, the PHMASSXX took a few cycles to settle and so these cycles were flagged suspect. During screening any obvious outliers and spikes were looked at in closer detail but it was not deemed that any spikes required flagging.

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

Colorimetric Microfluidic pH sensor

This sensor was specifically developed for autonomous seawater pH measurements by the National Oceaography Centre, Southampton in collaboration with the University of Southampton.

The seawater sample and thymol blue indicator solution are pumped by two syringe pumps and mixed in the flow cell in a static mixer before entering the absorption cell. The fluid distribution is controlled by four micro-inert valves. A three-wavelength LED light source transmits light through the absorption cell which is detected by a HR4000 spectrometer. The measurements are made close to in situ temperature (plus 0.2 degrees celsius) by placement of the microfluidic flow cell in the sampling chamber which has continuous access to the ship's underway seawater supply.

Measurements are made by first rinsing the flow cell with 300 µl of the sample before injecting 12 µl of indicator and determination of the absorption spectra. The remaining sample is then pumped through the system at a rate of 60 µl min^-1. The LED's wavelengths are 435 nm (25 nm full width half maximum (FWHM)), 596 nm (15 nm FWHM) and 750 nm (30 nm FWHM).

Further information can be found in the following publication.

BODC Processing of pH (continuous surface underway) onboard UKOA cruise JR20120601

Data Processing

Data were received in an Excel spreadsheet which was subsequently archived following BODC's procedures. The spreadsheet contained three sheets, Metadata, pH underway data and pH CTD bottle data, which were all saved as CSV files during archiving. Only the pH underway data is processed here. The data were transferred to BODC internal format using standard BODC processing procedures. During transfer it was noticed that the submitted data were not ordered chronologically and so during BODC processing the data were ordered by the time channel.

The originator's variables were mapped to BODC parameter codes as follows:

Screening

Post transfer analysis and crosschecks were applied according to BODC procedures. This involved the screening of data using BODC's in house visualisation software where any suspect data were flagged but not removed.

Originator's processing of pH (continuous surface underway) onboard UKOA cruise JR20120601

Data Acquisition and Analysis

The pH of the non-toxic water supply was continuously measured on board JR20120601 (JR271) using a custom made bench top colorimetric pH analyser. The ship's continuous underway supply was connected to the instrument where a syringe pump automatically withdrew a sample and injected the sample into the measurement cell. pH was measured by adding a coloured indicator to the seawater sample and measuring the colour of the mix. The indicator used was 2 mM Thymol Blue. Measurements were performed at close to in situ temperature at 0.6 ± 0.1°C. The pH sensor was developed by the Sensor Group at the National Oceanogrpahy Centre Southampton. The system ran between 03 JUN 2012 to the 01 JUL 2012 however there were interruptions for system performance checking, maintenance and when in ice covered waters.

Data Quality

The performance of the system was evaluated by running certified Tris buffer provided by the Scripps Institution of Oceanography. The consistency of the data was checked using continuous pCO₂ measurements and DIC/Alkalinity sampled on the underway supply every two hours and trends in other parameters such as chlorophyll, temperature, salinity and nutrients.

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: