Chlorine Oxide (L2__OCLO__)

The TROPOMI 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.