The Danish local scale models OSPM, OML-Multi, OML-Highway and UBM all apply the same scheme for NO2chemistry.

The scheme - referred to as the OSPM NO2 chemistry scheme - offers advantages over many other currently used schemes, such as those using photochemical equilibrium or the 'ozone limited approximation'. These simpler schemes can be derived as special cases of the OSPM scheme.

The details of this scheme is explained in a note. Further, the note illustrates the results of the scheme and the consequences of certain simplifications, namely those of assuming photochemical equilibrium, respectively using the 'ozone limited approximation'.

Link to the note: NO2 chemistry scheme in OSPM and other Danish models. prepared by Ruwim Berkowicz, Matthias Ketzel, Per Løfstrøm and Helge Rørdam Olesen. March 2011, 7 pp.