Case Studies: Understanding Climate Change

All EMRP projects engage widely with the user communities who will benefit from the research. For the Environment EMRP projects this included the climatology community, environmental monitoring agencies and laboratories, and key measurement instrumentation suppliers as well as the relevant technical committees and working groups in the standardisation community. Here we highlight a selection of early examples of the impact generated by these projects.

Improving atmospheric data

Spectro-analytical techniques used to identify and quantify concentrations of greenhouse and other gases in the atmosphere are based on the unique spectral ‘fingerprints’, or spectral lines, generated by molecules interacting with electromagnetic radiation. Accurate spectral line data is required to reduce measurement uncertainties and generate more robust data for climate predictions.

The EMRP project Spectral reference data for atmospheric monitoring has enabled the development and commissioning of a new measurement facility capable of generating greenhouse gas spectral line data with improved traceability to the SI. The spectral data generated within the project is due to be included in an upcoming revision of the HITRAN database, one of the most widely-used spectral databases in the world.

The project’s contribution will mark a significant increase in the amount of traceable spectral data available to researchers using HITRAN. One of the key users is TCCON, a network of 23 ground-based atmospheric monitoring stations distributed across the globe, which provide performance validation to satellite-borne spectral instruments. The improved data provided by TCCON-validated satellites will make a valuable contribution to reducing the uncertainties involved in climate models and support robust predictions of long-term climate change.

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Confidence in climate data

The UK Met Office generates some of the most comprehensive climate projections ever produced, to help decision-makers assess risk exposure to climate change and inform mitigation and adaptation strategies. These projections are guided by climate data from a number of sources, both historic and current.

The Met Office will use a new uncertainty evaluation method developed within the EMRP project European metrology for Earth observation and climate, to enable the combination of climate data collected on the most recent European Sentinel satellite missions with its existing datasets. This opens up a significant amount of additional climate data to the Met Office for climate monitoring and modelling purposes, improving the quality and range of measurements available to guide its climate projections.

The method and the research it is based on have also been assembled into a course and textbook for Earth observation scientists, which will be freely-available online in the near future. This is a significant step towards improving measurement uncertainty evaluation in the climate research community and will contribute to improved climate models and projections. 

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Ensuring accuracy in the upper atmosphere

To assess the impact of tiny variations in atmospheric composition on long-term climate change, the Earth observation community needs highly-accurate measurements of atmospheric composition. However, while carefully calibrated on the ground, instruments on board aircraft and satellites can degrade while in flight.

Within the EMRP project European metrology for Earth observation and climate, a new calibration facility was used to provide traceability for airborne spectroradiometers. Two novel, compact black-body radiation sources, developed in collaboration with University of Wuppertal, were calibrated using the new facility prior to use as transfer standards on board a research aircraft.

One of the first instruments to benefit was GLORIA, the first of a new generation of spectroradiometers for Earth observation. GLORIA’s novel infrared camera measures trace gases in the atmosphere with an unprecedented combination of vertical and horizontal resolution that relies upon highly-accurate calibration. The new transfer standards enabled the first traceable mid-infrared measurements of thermal emissions – a significant step forward in Earth observation research. This newly traceable technology can now be used on board balloons and satellites, plugging the gap in high-quality data needed for robust climate change assessment.

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Seeing ocean colour from space

Research buoys make local measurements of a range of variables essential to climate models, including ocean colour, which can be used as a measure of phytoplankton concentrations and provide vital information for monitoring the global carbon cycle.

The EMRP project European metrology for Earth observation and climate developed a novel easily-transportable light source, which can be used to calibrate instruments on buoys in situ. This provides traceability to the buoy’s measurements, and those provided by satellites, which are compared to the buoy’s and corrected when they pass overhead.

One of the first beneficiaries was BOUSSOLE, an international project supported by organisations including the European Space Agency and French space agency, CNES. Instrumentation on the BOUSSOLE buoy has now been calibrated using the new portable standard and is being used to confirm the response of the European Ocean Land Colour Instrument, recently launched on the Copernicus Sentinel 3 satellite. This is just one example of how the new calibration standard is improving the accuracy of ocean colour measurements, and ultimately supporting more robust carbon cycle trend analysis and climate monitoring.

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Understanding our oceans

Oceans are the largest active carbon sinks on Earth, absorbing more than a quarter of anthropogenic carbon emissions. The ocean’s interaction with the atmosphere, and its ability to absorb carbon dioxide, is strongly influenced by properties of seawater, such as salinity and acidity. Reliable and comparable measurements of these properties are of crucial importance to climate researchers, enabling them to detect small changes in ocean dynamics over decades and even centuries.

Salinity & temperature

The EMRP project Metrology for ocean salinity and acidity provided a reference method for ocean salinity, which makes practical salinity measurements traceable to the SI units through density measurements. Ocean Scientific International Ltd (OSIL) is going to incorporate density measurements into the preparation of its standard seawater, which is the only internationally-recognised calibration standard for practical salinity. This will provide traceability to ocean salinity measurements across the globe and allow the oceanography community to reliably identify even small changes.

Additionally, probes used to measure the speed of sound in seawater can now be traceably calibrated under typical operating conditions at newly-developed facilities at project partners PTB and INRIM. Measurements at sea have also confirmed the performance of a prototype transfer standard developed at INRIM, bringing easily achievable traceability to ship-based probes. Vessels equipped with such sensors could provide a cost-effective, extensive seawater temperature measurement network to supplement satellite data for climate models.

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The project also helped to establish a traceability chain for seawater pH by developing primary and reference methods for pH measurements. The team contributed validation methods to a new ISO standard (ISO/CD 18191) for pH and is working with the Scripps Institution of Oceanography - the sole provider of a seawater buffer solution used to calibrate field-based oceanographic instrumentation.

The team is also contributing to the two key influential committees that define seawater parameters and methods: the pH subgroup of the Joint Committee on the Properties of Seawater, which is responsible for maintaining and improving the seawater equation of state, a key tool in ocean science; and a new group of the International Union of Pure and Applied Chemists, which is using project outcomes to ensure greater harmonisation of the measurement methods used by the oceanographic community.

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Oxygen levels

EHP-Tekniikka, a provider of environmental monitoring services and equipment, took part in a comparison exercise, organised by the University of Tartu and project partner SYKE, to compare the dissolved oxygen measurements provided by commercially-available sensors to those made using the traceable Winkler titration method for the first time. Using a PONSEL OPTOD oxygen sensor - an optical sensor designed with an internal calibration capability - EHP-Tekniikka was able to directly compare the instrument’s response using a procedure developed within the project.

The positive results obtained have given confidence in this type of instrument’s internal calibration capability and its applicability for high-accuracy measurements of dissolved oxygen concentrations. 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.

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Building environmental metrology skills

A best practice uncertainty evaluation method, developed by the EMRP project Metrology for ocean salinity and acidity provided a key component of a new online course developed by project partner, the University of Tartu in Estonia. The best practice method was developed for use with the Winkler titration method, used to determine the concentration of dissolved oxygen in samples in water quality studies.

The online course, Estimation of measurement uncertainty in chemical analysis, has not only been taken by 700 students so far but is also being used by SP, the Technical Research Institute of Sweden, to train environmental testing laboratories working towards Nordtest accreditation. Nordtest is the Nordic area conformity assessment body whose role is to harmonise compliance with standards and remove barriers to trade across the Nordic countries, which includes the accreditation of measurement and testing and conformity assessment laboratories.

The project’s outputs are therefore not only contributing to important climate change research but are supporting the development of skills for practical and effective environmental monitoring.

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Taking calibration to the extremes

Accurate assessment of climate change relies on a world-wide network of atmospheric monitoring stations that provide high-quality data, which is comparable regardless of where it’s collected. The EMRP project Metrology for pressure, temperature, humidity and airspeed in the atmosphere is taking traceability to remote monitoring locations through a newly-developed portable calibration chamber for temperature, humidity and pressure sensors, known as EDIE.

EDIE was temporarily installed at Ny-Ålesund, a research community in Svalbard, enabling the island’s atmospheric monitoring instruments to benefit from traceable calibration without having to be transported to distant calibration laboratories and unavailable for long periods of time. EDIE has, for the first time, enabled on-site calibration of the ground instruments which contribute to the Global Climate Observing System Reference Upper-Air Network, in conditions closer to those encountered during operation in the harsh Arctic environment.

Further developments to EDIE are underway to make a more robust, compact version suitable for long-term installation in Ny-Ålesund - a first step towards a permanent Arctic calibration laboratory that will support multi-national climate observation and research at Svalbard.

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