The Sentinel-5P chlorine dioxide (OClO) slant column product was developed to monitor the daily global distribution of this trace gas in the Earth's atmosphere.

Chlorine dioxide can be used as a proxy for stratospheric chlorine activation, which leads to ozone depletion. While OClO is not directly involved in ozone destruction, its concentration is proportional to the abundances of ClO and BrO. With BrO concentrations being much less variable than those of ClO, OClO can be used as a quantitative measure of chlorine activation, at least at solar zenith angles around twilight.

Enhanced OClO columns are expected mainly in Polar spring in both hemispheres, during some volcanic eruptions, and in strong lee-wave events at high latitudes. The S5PI+ OClO project is one of the seven themes of ESA’s Sentinel-5p+ Innovation activity, which aims at developing products for the TROPOMI instrument on the Sentinel-5 Precursor satellite which are not yet part of the operational processor.

Information about OClO

The Sentinel-5P OClO processor is developed and maintained by the Institute of Environmental Physics, University of Bremen, IUP-UB. The validation of the product was performed by the Royal Belgian Institute for Space Aeronomy IASB-BIRA.

Available resources:

Product User Manual (PUM)
Algorithm Theoretical Baseline Document(ATBD)
Validation Report (VR)

Processor version history

  • v01.00.01 (2024-04-15)
    • Minor bug fix
  • v01.00.00 (2024-04-05)
    • 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.


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

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.