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Understanding our oceans

The EMRP project ‘Metrology for ocean salinity and acidity’ developed measurement methods, standards and tools to improve the accuracy of ocean data used for climate monitoring and modelling.

The project’s outputs enable the traceable calibration of sensor networks and satellite systems.

This will allow scientists to reliably identify small changes in long-term oceanographic data series.

1. Understanding ocean acidity
Oceans are the largest active carbon sinks on Earth. As the amount of carbon dioxide in the Earth’s atmosphere has increased, so too has the acidity of our oceans. Small changes in acidity have a significant effect on the marine eco-system. Monitoring pH is vital if we are to protect marine life and maintain the effectiveness of the ocean as a carbon reservoir. 

This case study shows how the project has helped to establish the traceability chain for seawater pH with the development of primary and reference methods for pH measurements. These accurate methods have been adopted by the oceanographic community. 

In addition, the project team contributed validation methods to new ISO standard for using spectrophotometric methods to determine pH in seawater. They are also working with an oceanographic institute which is the sole provider of a seawater buffer solution, which resists a change in pH when a small amount of acid is added, used to calibrate field-based oceanographic instrumentation.

Read the full ‘Understanding ocean acidity’ case study 

2. Understanding our oceans
Oceans play a key role in regulating the global climate system. The interaction of oceans with the Earth’s atmosphere is strongly linked to seawater properties such as salinity. Oceans must be accurately monitored to identify long-term climate trends and measurements of their properties must be comparable regardless of where and when they are made.

This case study shows how the project provided a reference method for ocean salinity, which makes practical salinity measurements traceable. Possible long-term drifts in the chemical composition of the standard seawater solution can now be accounted for and eliminated.

Thanks to this successful project the measurement community has been invited to sit on the prestigious Joint Committee for the Properties of Seawater, the organisation responsible formaintaining and improving seawater standards. The project outputs will make a substantial contribution towards improving the accuracy of ocean salinity and density measurements which provide key input into global climate models.

Read the full ‘Understanding our oceans’ case study 

3. Monitoring ocean oxygen levels 
Decreasing oxygen levels in the world’s oceans, driven by increasing ocean temperatures, are expected to have a major impact on the carbon cycle and our climate, as well as ocean life.

This case study shows how a comparison exercise organised by the project has helped promote best measurement practice within the oceanography community, including a provider of environmental monitoring services and equipment developing a new oxygen sensor.

Monitoring oxygen levels in the world’s oceans is important in the development of robust models for climate change and evaluating the oceans ability to absorb carbon dioxide.

This validation paves the way to increased use of automated oxygen sensors and will lead to a significant increase in the oceanography community’s capacity to produce high-accuracy dissolved oxygen data for robust climate trend analysis.

Read the full ‘Monitoring ocean oxygen levels’ case study

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