Short-lived atmospheric trace gases, nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), formaldehyde (HCHO), and ammonia (NH3) are the subject of focus for the latest project to be added to ESA's Climate Change Initiative.

The project aims to deliver consistent decades-long climate data records using data collected from a range of satellite instruments including GOME, SCIAMACHY, GOME-2, OMI, TROPOMI, IASI, and MOPITT.

Trends in HCHO columns between 2005 and 2015 observed by OMI (left) and simulated with a global model (right). The positive trends seen at high latitudes are due to the warming climate and are well reproduced by the model.

Observations of these precursor gases are needed to develop emission-based scenarios for radiative forcing by tropospheric ozone and secondary aerosols, due to both anthropogenic and natural sources. The impact of this basket of gases on the climate is sufficient enough to warrant its inclusion as one of 54 Essential Climate Variables defined by the Global Climate Observing System.

A series of user case studies will be developed including:

  • Impact of NO2 and CO climate data records on CAMS reanalysis
  • Evaluation of NO2 and HCHO emission inventories
  • Evaluation of GEOS-Chem NO2 and HCHO over Tropics
  • Drivers of HCHO observed variability over African rainforests

The project which runs until mid-2025 is led by Michel van Roozendael of the Belgian Institute for Space Aeronomy.