As part of the commitment to reduce green-house gas (GHG) emission as stated in the Paris agreement, trustworthy, accurate and independent ways of measuring GHG are required. Gases know no border: a global system is therefore needed with international collaborations to set a GHG emission monitoring system that includes measurements from satellites, airborne platforms, and ground-based instruments. The ground component of this system is particularly important to calibrate and validate observations from a growing satellite fleet. To do this a measurement of the whole of the air column, from the ground to the top of the atmosphere needs to be taken.
By looking at the Sun through the atmosphere, an instrument called a Fourier Transform Spectrometer (FTS), together with processing algorithm, is able to get an accurate and precise average reading for the whole column for a range of greenhouse gases, including carbon dioxide and methane. The Total Carbon Column Observing Network (TCCON), initiated by the California Institute of Technology in the USA, is a network of ~31 FTS located across the world from Lauder, New Zealand to Eureka, Canada. This network adheres to strict quality metrics to ensure it is the gold standard in remote measurement of GHG.
The latest installation to receive accreditation to join the TCCON is run by the RAL Space Spectroscopy Group and is located at the Science and Technology Facilities Council's (STFC) Rutherford Appleton Laboratory in Oxfordshire. The highly accurate observing station has been developed over the last five years with support from STFC and the National Centre of Earth Observation (NCEO) and has already produced and processed one year of atmospheric GHG data, required for the stringent network accreditation process.
The network nature of TCCON, and its spread across the Earth, is essential, and more members providing high quality measurements significantly increase the quality of a global GHG observing system. High geographical diversity ensures that observations from greenhouse gas observation satellites can be validated more accurately according to a wide range of geographic, topographic, and meteorologic conditions.
The UK location of the RAL Space instrument is of particular interest to characterize the GHG local sources but also to characterize exchanges of GHG between the north Atlantic and the European continent. It's colocation with the National Satellite Test Facility can also unlock novel applications for pre-flight satellite instrument characterisation.
The newly accredited observing station will also ensure and promote UK involvement in the international effort to climate assessment and mitigation.
Dr Damien Weidmann, Laser Spectroscopy Group Leader at RAL Space said:
“Countries have signed up to the Paris agreement to mitigate climate change, which implies a reduction in GHG emission. This newly established UK facility is essential in enabling accountability and trust in GHG emission reporting. It is also essential to ensure we make the most out of a very expensive space-borne infrastructure observing GHGs."
Development of the site was supported by RAL Space, the Science and Technology Facilities Council, and the Natural Environment Research Council's NCEO.