A comprehensive performance evaluation of the air quality model BOLCHEM to reproduce the ozone concentrations over Italy

A comprehensive model evaluation has been conducted for BOLCHEM over the whole of Italy during four periods favorable to ozone photochemistry: 1–3 June, 1–4 July, 5–7 August and 20–24 January during the year 1999. Two photochemical mechanisms, SAPRC90 and CB-IV, have been employed to simulate the evolution of ozone, taking into account the Italian and European inventories and maritime emissions. The comparison of simulated and measured ozone concentrations demonstrates that the model is able to forecast well the daily variation of ozone with both mechanisms, in particular during the summer, when the ozone photochemistry is more active. The discrepancies between the ozone predicted with the SAPRC90 and CB-IV mechanisms are similar to those previously reported in the literature: SAPRC90 leading to higher ozone concentrations than CB-IV due to the differences in their representation of VOC mixture. However, for both photochemical mechanisms, the model skill scores are good, proving the reliability of the model for regional scale applications.