Data assimilation of surface air pollutants (O3 and NO2) in the regional-scale air quality model AURORA

► Applied a bias-aware optimal interpolation in the air quality model AURORA in retrospective mode. ► Hollingsworth-Lönnberg method to estimate error covariance matrices. ► The validation was carried out by using “leave ten out approach”. ► The method proves to be very promising especially in retrospective simulation.