Search

In the framework of the Chemistry and Aerosol Mediterranean Experiment project (ChArMEx, http://charmex.lsce.ipsl.fr), we study the evolution of surface ozone (O3) over the Mediterranean Basin (MB) with a focus on summertime over the time period 2000-2100, using the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) outputs from 11 models. We consider three different periods (2000, 2030 and 2100) and the four Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) to study the changes in the future ozone trend and its budget. We use a statistical approach to compare and discuss the results of the models. We discuss the behavior of the models that simulate the surface O3 over the MB. The ensemble mean of ACCMIP models simulates very well the annual cycle of surface O3. Compared to measured summer surface O3 datasets, we found that most of the models overestimate surface O3 and underestimate its variability over the most recent period (1990-2010) when independent observations are available. Compared to the reference period (2000), we found a net decrease in the ensemble mean surface O3 over the MB in 2030 (2100) for 3 RCPs: -13 % (-36 %) for RCP2.6, -7 % (-22 %) for RCP4.5 and -11 % (-33 %) for RCP6.0. The surface O3 decrease over the MB for these scenarios is much more pronounced than the relative changes of the tropospheric ozone burden. This is mainly due to the reduction in O3 precursors and to the NOx-limited regime over the MB. For the RCP8.5, the ensemble mean surface O3 is almost constant over the MB from 2000 to 2100. We show how the future climate change and the increase in CH4 concentrations can offset the benefit of the reduction in emissions of O3 precursors over the MB. [ABSTRACT FROM AUTHOR]