Article Index

Sentinel-5p TROPOMI provides one SO2 data product:

Sulphur dioxide

 

Validation Summary

 

The Sentinel-5p TROPOMI L2_SO2 (NRTI and OFFL) sulphur dioxide column data are found in general good agreement with ground-based MAX-DOAS and PGN measurements and with other satellite observations from OMI and S-NPP OMPS. The bias and dispersion with respect to validation data are typically below 0.2 DU. From these comparisons it can be concluded that over polluted regions the mission requirements are fulfilled. Over volcanic plumes the requirement on the bias is fulfilled, while the dispersion can exceed slightly the requirement on the random component of the uncertainty. Here it should be noted that detailed validation of SO2 in volcanic plumes based on ground based observations is still lacking.

Validation of the UPAS processor upgrade to version 02.01.03 released in July 2020 show good consistency of the SO2 data product before and after the processor switch. Later upgrades to version 02.01.04 in December 2020, to version 02.02.01 in July 2021, and to version 02.03.00 in March 2022 (improved background correction), had no effect on S5P L2_SO2 data quality.

 

 


Sentinel-5p TROPOMI SO2 total column data is validated through comparisons to the following correlative ground-based measurements.

  • Direct-sun measurements from Pandora spectrometers of the PGN network. Note that these are still in demonstration phase. Pandora direct-sun measurements (Knepp et al., 2015; Fioletov et al., 2016; McLinden et al., 2021) are sensitive to the entire column.
  • Multi-axis DOAS UV-visible measurements (MAX-DOAS). MAX-DOAS measurements (e.g., Wang et al., 2017; Theys et al., 2015) are mainly sensitive to the lower tropospheric column.

References

Knepp, T. et al., Estimating surface NO2 and SO2 mixing ratios from fast-response total column observations and potential application to geostationary missions, J. Atmos. Chem., 2015, 72, 261-286, doi.org/10.1007/s10874-013-9257-6

Fioletov, V.E. et al., Sulfur dioxide (SO2) vertical column density measurements by Pandora spectrometer over the Canadian oil sands, Atmos. Meas. Tech., 2016, 9, 2961-2976, doi.org/10.5194/amt-9-2961-2016

McLinden, C.A. et al., Inconsistencies in sulfur dioxide emissions from the Canadian oil sands and potential implications, Environmental Research Letters, 2021, 16, 014012, doi.org/10.1088/1748-9326/abcbbb

Wang, Y. et al., Validation of OMI, GOME-2A and GOME-2B tropospheric NO2, SO2 and HCHO products using MAX-DOAS observations from 2011 to 2014 in Wuxi, China: investigation of the effects of priori profiles and aerosols on the satellite products, Atmos. Chem. Phys., 2017, 17, 5007-5033, doi.org/10.5194/acp-17-5007-2017

Theys, N. et al. Sulfur dioxide vertical column DOAS retrievals from the Ozone Monitoring Instrument: Global observations and comparison to ground-based and satellite data,
J. Geophys. Res. Atmos., 2015, 120, 1-22, doi.org/10.1002/2014jd022657

 


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Quarterly Validation Report of the Copernicus Sentinel-5 Precursor Operational Data Products #16: April 2018 - August 2022

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