A Parameterization of Heterogeneous Hydrolysis of N2O5 for 3-D Atmospheric Modelling

During night-time, the heterogeneous hydrolysis of N 2O 5 on the surface of deliquescent aerosol particles represents a major source for the formation of HNO 3 and leads to an important reduction of NO x in the atmosphere. In Chen et al., Atmos. Chem. Phys. 18:673–689, 2018 [5], we investigate an improved parameterization of the heterogeneous N 2O 5 hydrolysis. This approach is based on laboratory experiments and takes into account the temperature, relative humidity, aerosol particle composition as well as the surface area concentration. The parametrization was implemented in the online coupled model system COSMO-MUSCAT (Consortium for Small-scale Modelling and Multi-Scale Chemistry Aerosol Transport, https://cosmo-muscat.tropos.de). In Chen et al., Atmos. Chem. Phys. 18:673–689, 2018 [5], the modified model was applied for the simulation of the HOPE-Melpitz campaign (10–25 September 2013) where especially the nitrate prediction over western and central Europe was analysed. The modelled particulate nitrate concentrations were compared with filter measurements over Germany. In this first study, the particulate nitrate results are significantly improved by using the developed N 2O 5 parametrization, particularly if the particulate nitrate was dominated by the local chemical formation (September 12, 17–18 and 25). The aim of the current study consists in an evaluation over a longer time period for different meteorological conditions and emission situations. For this reason, we have simulated the period from March to November 2010. The results were compared with other approaches and evaluated by filter measurements. The improvement was confirmed for the results in spring and autumn, but nitrate is strongly over-predicted also for the new parametrization during the summer time