An Assessment of the Relative Importance of Factors Impacting Surface UV Radiation Based on Simulations of the 6th Phase of the Coupled Intercomparison Project

Abstract

Aerosols, ozone, surface reflectivity, and clouds are, among other factors, important for the modulation of UV radiation levels at the Earth’s surface. In this study, these variables were extracted from climate model integrations that contributed to CMIP6 and from MACC global reanalysis provided by the CAMS. From the 1950s until the end of the 21st century and for various shared socioeconomic pathways considered by CMIP6, we conclude that total ozone will increase globally in 2100 by up to 11% under SSP5–8.5 relative to the 1950s, while under SSP1–2.6, ozone is not projected to recover to pre-ozone depletion levels. AOD at 550 nm shows reductions in 2090–2100 over the Northern Hemisphere of up to −0.38. Compared to CAMS, CMIP6 models show a general overestimation for total ozone of up to 2.5% in extra-polar regions for models with interactive chemistry. This implies systematically lower UV radiation from models based on these projections.

Keywords

• CMIP6
• ozone
• surface reflectivity
• aerosol
• cloud modification factor