EGU22-1627
https://doi.org/10.5194/egusphere-egu22-1627
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Advanced retrieval of sulfur dioxide over Asia using TROPOMI and GEMS satellite sensors

Nicolas Theys1, Isabelle De Smedt1, Caroline Fayt1, Jeroen van Gent1, Christophe Lerot1, Hanlim Lee2, Jeonghyeon Park2, Hyunkee Hong3, and Michel Van Roozendael1
Nicolas Theys et al.
  • 1BIRA-IASB, Bruxelles, Belgium (theys@aeronomie.be)
  • 2Division of Earth Environmental System Science, Major of Spatial Information Engineering, Pukyong National University, Yongso-ro 45, Nam-gu, Busan 48513, Korea
  • 3National Institute of Environmental Research, Hwangyong-ro 42, Seo-gu, Incheon 22689, Korea

The high spatial resolution TROPOspheric Monitoring Instrument (TROPOMI) launched in 2017 onboard the Sentinel-5 Precursor (S5P) platform provides important information on global volcanic and anthropogenic SO2 emissions, with an unprecedented level of details. More recently, the Geostationary Environmental Monitoring System (GEMS) was launched onboard the GEO-KOMPSAT-2B satellite in February 2020. GEMS has the unique capability of sensing SO2 over Asia at hourly resolution, offering great perspectives in monitoring and understanding emission process and pollution transport in the atmosphere. GEMS is the first satellite sensor of a geostationary constellation with the European (Sentinel-4) and US (TEMPO) counterparts.

In a recent study (Theys et al., 2021), we proposed an approach called Covariance-Based Retrieval Algorithm (COBRA), different from the classical Differential Optical Absorption Spectroscopy (DOAS). Application of COBRA to TROPOMI SO2 column retrievals leads to a significant reduction of the retrieval noise and biases as compared to the TROPOMI operational (DOAS-based) SO2 product. COBRA even reveals new emission sources in long-term averaged SO2 maps.

In this presentation, we apply COBRA for the retrieval of SO2 from GEMS spectra. The resulting SO2 vertical columns are presented and evaluated against different satellite data sets (GEMS L2 SO2 operational product, and TROPOMI SO2 COBRA and operational products) and ground-based measurements.  While GEMS measures the same location several times per day, it is crucial to understand the retrieval bias and how it varies under varying observation geometry. This aspect and possible corrections will be discussed extensively.

Theys, N., Fioletov, V., Li, C., De Smedt, I., Lerot, C., McLinden, C., Krotkov, N., Griffin, D., Clarisse, L., Hedelt, P., Loyola, D., Wagner, T., Kumar, V., Innes, A., Ribas, R., Hendrick, F., Vlietinck, J., Brenot, H., and Van Roozendael, M.: A Sulfur Dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources, Atmos. Chem. Phys., 21, 16727–16744, https://doi.org/10.5194/acp-21-16727-2021, 2021.

How to cite: Theys, N., De Smedt, I., Fayt, C., van Gent, J., Lerot, C., Lee, H., Park, J., Hong, H., and Van Roozendael, M.: Advanced retrieval of sulfur dioxide over Asia using TROPOMI and GEMS satellite sensors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1627, https://doi.org/10.5194/egusphere-egu22-1627, 2022.