The CHIMERE chemistry-transport model v2023r1

A new version of the CHIMERE model is presented. This version contains both computational and physico-chemical changes. The computational changes make it easy to choose the variables to be extracted as a result, including values of maximum sub-hourly concentrations. Performance tests show that the model is 1.5 to 2 times faster than the previous version for the same set-up. Processes have been modified and updated such as turbulence, transport schemes and dry deposition. Optimization was also performed for the management of emissions such as anthropogenic and mineral dust. The impact of fires on wind speed, soil properties and LAI was added. Pollen emissions, transport and deposition were added for birch, ragweed, olive, grass. The model is validated with a simulation covering Europe with 60×60 km resolution and the entire year of 2019. Results are compared to various measurements, and statistical scores show that the model provides better results than the previous versions.