Operational ozone forecasts for the region of Copenhagen by the Danish Meteorological Institute

The Danish Meteorological Institute (DMI) has developed an operational fore casting system for ozone concentrations in the Atmospheric Boundary Layer; this system is called the Danish Atmospheric Chemistry FOrecasting System ( DACFOS). At specific sites where real-time ozone concentration measurements are available, a statistical after-treatment of DACFOS' results adjusts th e next 48 h ozone forecasts. This post-processing of DACFOS' forecasts is b ased on an adaptive linear regression model using an optimal state estimato r algorithm. The regression analysis uses different linear combinations of meteorological parameters (such as temperature, wind speed, surface heat fl ux and atmospheric boundary layer height) supplied by the Numerical Weather Prediction model DMI-HIRLAM. Several regressions have been tested for six monitoring stations in Denmark and in England, and four of the linear combi nations have been selected to be employed in an automatic forecasting syste m. A statistical study comparing observations and forecasts shows that this system yields higher correlation coefficients as well as smaller biases an d RMSE values than DACFOS; the present post-processing thus improves DACFOS ' forecasts. This system has been operational since June 1998 at the DMI's monitoring station in the north of Copenhagen, for which a new ozone foreca st is presented every 6 h on the DMI's internet public homepage. (C) 2001 E lsevier Science Ltd, All rights reserved.