EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Validation of satellite OClO products from S5P/TROPOMI and MetopA and B/GOME2 

Gaia Pinardi1, Michel Van Roozendael1, François Hendrick1, Andreas Meier2, Andreas Richter2, Thomas Wagner3, Myojeong Gu3, Udo Friess4, Kimberly Strong5, Kristof Brognar5, Ramina Alwarda5, Richard Querel6, Margarita Yela7, Cristina Prados-Roman7, and Pieter Valks8
Gaia Pinardi et al.
  • 1Belgian Institute for Space Aeronomy (BIRA-IASB), Chemistry and Physics of Atmospheres, Brussels, Belgium
  • 2Institut für Umweltphysik, Universität Bremen, Bremen, Germany
  • 3Max Planck Institute for Chemistry, Mainz, Germany
  • 4Institut für Umweltphysik, Universität Heidelberg, Heidelberg, Germany
  • 5University of Toronto, 60 St George St., Toronto, Ontario, M5S 1A7, Canada
  • 6NIWA, Lauder, New Zealand
  • 7INTA, Instituto Nacional de Técnica Aeroespacial, Torrejón de Ardoz, Madrid, Spain
  • 8German Aerospace Center, DLR, Weßling, Germany

Chlorine dioxide is an indicator for chlorine activation in the stratosphere, of importance for understanding spring-time ozone depletion processes in the polar regions of both hemispheres. Within the EUMETSAT AC SAF working group, chlorine dioxide (OClO) was retrieved from the GOME-2 instruments on MetOp-A and MetOp-B platforms, respectively over the time periods 2007-2016 and 2012-2016. Moreover, recent work performed as part of the S5p+ Innovation programme has led to the creation of an additional dataset derived from the TROPOMI instrument, extending the OClO time series in 2018-2020.

This study analyses the quality of both OClO slant column (SCD) datasets by comparing them to ground-based DOAS zenith-sky measurements at a selection of 8 stations in Arctic and Antarctic regions: Eureka (80°N), Ny Alesund (79°N), Kiruna (68°N), Harestua (60°N), Marambio (64°S), Belgrano (78°S), Neumayer (71°S) and Arrival Heights (78°S). To allow for comparison with satellite data, ground-based OClO spectral analyses are performed using yearly fixed reference spectra recorded at low SZA in the absence of chlorine activation. Furthermore, an additional bias-correction is applied in post-processing to generate a consistent long-term OClO data record covering the 2007-2020 period.

Daily comparisons of satellite and ground-based SCD data pairs corresponding to similar SZA conditions are performed, assuming similar stratospheric light paths in satellite nadir and ground-based zenith-sky geometries. Daily mean OClO SCD time-series show that satellite and ground-based observations agree well at all stations in terms of short-term variability and seasonal variation. Linear regression plots show a correlation coefficient R of about 0.97, a slope of 0.9 and an intercept of less than 1x1013 molec/cm² for TROPOMI, while for GOME-2 results are more noisy and tend to be biased low, with correlation coefficients between 0.76 and 0.88, slopes between 0.65 and 0.74 and intercepts up to 2.4 x1013 molec/cm².

How to cite: Pinardi, G., Van Roozendael, M., Hendrick, F., Meier, A., Richter, A., Wagner, T., Gu, M., Friess, U., Strong, K., Brognar, K., Alwarda, R., Querel, R., Yela, M., Prados-Roman, C., and Valks, P.: Validation of satellite OClO products from S5P/TROPOMI and MetopA and B/GOME2 , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8446,, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.