Supporting the World Meteorological Organization Global Atmosphere
Watch programme WMO-GAW

Ensuring confidence in long-term climate monitoring data

The National Physical Laboratory (NPL) is the Central Calibration Laboratory (CCL) for non-methane hydrocarbons (NMHCs) and nitrogen oxides (NO_x) within the World Meteorological Organization Global Atmosphere Watch (WMO-GAW) programme.

NPL and the WMO have recently renewed both of these agreements and expanded their scope. 

• The expanded scope for the NMHCs now covers all 10 of the NMHCs (ethane, propane, isobutane, n-butane, acetylene, isopentane, n-pentane, isoprene, benzene and toluene) identified as of key importance for global monitoring of atmospheric composition in GAW Report 171 https://library.wmo.int/idurl/4/47478.
• The expanded scope for NO_x now includes both nitrogen monoxide (NO) and nitrogen dioxide (NO₂), which are both identified as of key importance  for global monitoring of atmospheric composition in GAW Report 195 https://library.wmo.int/idurl/4/60006.

NPL Primary Reference Materials (PRMs) are produced gravimetrically according to ISO 6142-1, are traceable to the international system of units (SI) through key comparisons organised by the Consultative Committee on Amount of Substance (CCQM) and represent the highest point in the traceability chain.

Read our Memorandum of Understanding (MoU) agreements with the WMO 

NPL has been the central calibration laboratory (CCL) for non-methane hydrocarbons (NMHCs) since 2010 and Nitrogen Oxides (NOx = NO + NO2) since 2016. Download Memorandum of Understanding

Contact us for all Primary Reference Material enquiries