Ultraviolet Radiation modelling using output from the Chemistry Climate Model Initiative - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Atmospheric Chemistry and Physics Discussions Year : 2018

Ultraviolet Radiation modelling using output from the Chemistry Climate Model Initiative

Sophie Godin-Beekmann
Slimane Bekki
Sandip Dhomse
  • Function : Author
  • PersonId : 981757
Rong-Ming Hu
  • Function : Author


We have derived values of the Ultraviolet Index (UVI) at solar noon from the Tropospheric Ultraviolet Model (TUV) driven by ozone, temperature and aerosol fields from the first phase of the Chemistry-Climate Model Initiative (CCMI-1). Since clouds remain one of the largest uncertainties in climate projections, we simulated only clear-sky UVI. We compared the UVI climatologies obtained from CCMI and TUV against present-day climatological values of UVI derived from satellite data (the OMI-Aura OMUVBd product) and ground-based measurements (from the NDACC network). Depending on the region, relative differences between the UVI obtained from CCMI and TUV and ground-based measurements ranged between −4 % and 11 %. We calculated the UVI evolution throughout the 21st century for the four Representative Concentration Pathways (RCPs 2.6, 4.5, 6.0 and 8.5). Compared to 1960s values, we found an average increase in UVI in 2100 (of 2–4 %) in the tropical belt (30° N–30° S). For the mid-latitudes, we observed a 1.8 to 3.4 % increase in the Southern Hemisphere for RCP 2.6, 4.5 and 6.0, and found a 2.3 % decrease in RCP 8.5. Higher UV indices are projected in the Northern Hemisphere except for RCP 8.5. At high latitudes, ozone recovery is well identified and induces a complete return of mean UVI levels to 1960 values for RCP 8.5 in the Southern Hemisphere. In the Northern Hemisphere, UVI levels in 2100 are higher by 0.5 to 5.5 % for RCP 2.6, 4.5 and 6.0 and they are lower by 7.9 % for RCP 8.5. We analysed the impacts of greenhouse gases (GHGs) and ozone-depleting substances (ODSs) on UVI from 1960 by comparing CCMI sensitivity simulations (1960–2100) with fixed GHGs or ODSs at their respective 1960 levels. As expected with ODS fixed at their 1960 levels, there is no large decrease in ozone levels and consequently no sudden increase in UVI levels. With fixed GHG, we observed a delayed return of ozone to 1960 values, the same signal is observed on UVI, and looking at the UVI difference between 2090s values and 1960s values, we found an 8 % increase in the tropical belt during the summer of each hemisphere. Finally, we show that, while in the Southern Hemisphere UVI is mainly driven by total ozone column, in the Northern Hemisphere both total ozone column and aerosol optical depth drive UVI levels, with aerosol optical depth having twice as much influence on UVI as total column does.
Fichier principal
Vignette du fichier
Ultraviolet_radiation_modelling_using_output_from_the_chemistry_climate_model_initiative.pdf (1.82 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-02265790 , version 1 (10-07-2018)
insu-02265790 , version 2 (12-08-2019)





Kévin Lamy, Thierry Portafaix, Beatrice Josse, Colette Brogniez, Sophie Godin-Beekmann, et al.. Ultraviolet Radiation modelling using output from the Chemistry Climate Model Initiative. Atmospheric Chemistry and Physics Discussions, 2018, ⟨10.5194/acp-2018-525⟩. ⟨insu-02265790v1⟩
794 View
395 Download



Gmail Facebook X LinkedIn More