CHOCHO (glyoxal) is a good indicator for emissions of Volatile Organic Compounds (VOCs) as it is produced as a secondary product from their oxidation as well as directly emitted from combustion processes. Its short lifetime of a few hours leads to enhanced signals at proximity of its production sources. CHOCHO is also involved into the production of secondary organic aerosols (SOA), which affect both air quality and climate forcing.

The CHOCHO tropospheric column dataset generated by S5P-PAL is a pre-operational TROPOMI product relying on the algorithm developed by BIRA-IASB as part of the GLYRETRO project, one of the component of the ESA S5p+Innovation programme.

Information about CHOCHO

The CHOCHO processor is developed and maintained by BIRA-IASB.

All users are encouraged to first look at the Product User Manual (PUM) for a general description on how to use the CHOCHO product.

Details on the algorithm, product format and how it has been validated are available in the documents below.

Available resources:

Algorithm Theoretical Baseline Document (ATBD)
Product User Manual (PUM)
Validation Report (VR)
Reference peer-reviewed article:

Processor version history

  • v01.00.00 (2022-10-20)
    • Initial public release

Known issues

The dataset does not provide a full timeline and products for several orbits are known to be missing. Information about known acquisition gaps in the data can be found on the Mission Status webpage of Sentinel-5P.

Interactive product browsing and download

Available product files can be selected and downloaded using the SpatioTemporal Asset Catalog (STAC) browser interface.

This browser interface does not currently support the more advanced search queries made possible by the STAC API. For that you will need to programmatically query the S5P-PAL STAC endpoint.


This service is provided as part of the Sentinel-5P Product Algorithm Laboratory (S5P-PAL) and contains modified Copernicus Sentinel data processed by S[&]T.

Questions regarding this service can be send to the ESA EO Support Helpdesk.