The ocean plays a vital role in the global climate system, and as a result human activity is both affected by and contributes to changes to the ocean. Marine ecosystems are crucial for maintaining biodiversity, accounting for 90% of the habitable space on the planet. They also produce over 50% of the planet’s oxygen and provide a source of food and medicine. As a consequence of its capacity to act as a carbon sink, ocean acidification is rapidly changing marine environments. As global temperatures increase, sea levels are rising, affecting the livelihoods of coastal communities. Understanding the state of the ocean requires frequent, global observations of physical, biological and chemical variables. Very small changes in these variables can have significant impacts on ocean systems, so characterising the ocean presents many significant measurement challenges.

Our ocean section covers the metrological contribution to support in situ measurements of Global Climate Observing System (GCOS) Oceanic Essential Climate Variables (ECVs) along with the broader Essential Ocean Variables defined by the Global Ocean Observing System. These include physical (e.g. temperature, salinity, currents, ice), biogeochemical (e.g. dissolved gases and nutrients, acidification, particulate matter and tracers) and biological (e.g. phytoplankton, ocean sound) variables. Alongside climate applications, the Ocean Observation section reflects the broader variety of economic, societal, and environmental perspectives relating to the sustainable use of ocean resources.

Case Studies

Examples of measurement science for oceans can be found in the selected case studies below:

Understanding our oceans - Salinity & Temperature

The oceanography community most commonly measures ocean salinity using the ‘Practical Salinity Scale’, which is based on comparing seawater electrical conductivity with the conductivity of a commercially available standard solution made from North Atlantic seawater. This salinity is then used to calculate other properties, like...

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Monitoring ocean oxygen levels

Today, the majority of dissolved oxygen measurements made by the oceanographic community are made using amperometric and optical sensors. While the performance of these sensors has improved dramatically over recent years, accurate measurements are still difficult to obtain due to the influence of numerous sources of measurement...

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Understanding ocean acidity

As the amount of carbon dioxide in the Earth’s atmosphere has increased, so too has the acidity of our oceans. The carbon balance between the oceans and the earth’s atmosphere is extremely delicate with small changes in acidity having a significant effect on the marine eco-system. Monitoring pH is vital if we are to protect mar...

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Building environmental metrology skills

Science and engineering students and many industrial process and quality control professionals require a grounding in best measurement practices and the calculation of measurement uncertainties, in order to produce accurate, comparable data to inform decision making. This knowledge often forms part of university syllabuses but ...

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