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Site monitoring greenhouse gases approved as GAW regional site

The Heathfield Tall tower site, managed by the Emissions and Atmospheric Metrology Group at NPL, has been accepted as a World Metrological Organisation (WMO) Global Atmospheric Watch (GAW) Regional site.

GAW is the only long-term global programme providing a framework for observations and assessment of the state and development of environmental issues related to atmospheric chemical composition.

The observations of greenhouse gases (GHGs) coordinated by WMO and GAW help support society in guiding climate actions and improving understanding of the carbon cycle. The data is used to produce the annual WMO Greenhouse Gas Bulletin, and guide analyses and assessments that support the United Nations Framework Convention on Climate Change (UNFCCC) and the Inter-governmental Panel on Climate Change (IPCC).


Due to the site’s location, in a small market town in East Sussex, far from strong sources of local pollution, measurements from this site are used to calculate emission maps of trace gas species in the UK in combination with other measurement stations in the UK (Ridge Hill, Tacolneston and Bilsdale) and Ireland (Mace Head).

Air samples (CO2, CH4, CO, N2O, NO2, O3, SF6 and Rn-222) are taken from a line sampling 100 meters up a tall tower for all gases. CO2, CH4 and CO are also measured at a height of 50 m above ground level. This gives the tower a large sampling footprint covering the South East of England and Northern Europe. Heathfield is a relatively newly established site providing high-precision data on GHG observations. These observations show a clear increase in baseline CO2, CH4, N2O and SF6 mole fraction and capture the seasonal and diurnal cycles of these key gases.

This helps to quantify UK GHG emissions, and when combined with regional inversion modelling, reduce the uncertainty and improve the spatial and temporal resolution which will provide better information for future analyses, such as the UK carbon budget.

The site’s long-term commitments for observations are supported by NPL as the UK’s National Metrology Institute. Work at the station contributes to the UK-DECC (Deriving Emissions relating to Climate Change) project, led by the Met Office and University of Bristol, which aims to verify the UK’s GHG inventory using atmospheric measurements.


It is also a primary measurement site for NERC’s-large grant DARE-UK (detection and attribution of regional greenhouse gas emissions in the UK) forming collaborations with the University of Edinburgh, University of Bristol, University of East Anglia, and Royal Holloway University of London for deployment of new measurement and sampling techniques.

Dr. Caroline Dylag, Higher Research Scientist, NPL states: “Atmospheric measurements are crucial in understanding our global climate and international collaboration is required to further our scientific understanding. The recognition of our Heathfield atmospheric monitoring site under the WMO’s GAW programme will allow NPL’s measurements of atmospheric composition to be used by a global research community. Through improved monitoring and modelling of greenhouse gases, we can verify that climate change mitigation policies are working.”

12 Nov 2020