The influence of emission changes on ozone concentrations and nitrogen deposition into the southern North Sea

Abstract

The impact of changes in amount of emission for NO X (Nitrogen monoxide NO + Nitrogen dioxide NO 2 ) and NMVOC (Non Methane Volatile Organic Compounds) on concentrations of ozone (O 3 ), NO x , nitric acid (HNO 3 ) and on nitrogen deposition in the area of the southern North Sea are investigated. One reference case for the period 16 June till 20 June, 1998 and six emission scenarios are calculated. Spatial and temporal emission patterns are kept and overall emission factors are used that correspond to years 1998 (reference), 1970 and 2010. Some more artificial emission scenarios are constructed to investigate the effect of a changed ratio of NO x to NMVOC emissions. The meteorology is unchanged for all scenarios. The studies are performed with the meteorology/chemistry model M-SYS (METRAS/MECTM) including a simple aerosol chemistry and using a horizontal resolution of 8 km. Changes in emissions of NMVOC and NO x cause nonlinear changes in O 3 , NO x and HNO 3 concentrations. The concentration changes depend on emission changes and on changes in the ratio of NMVOC to NO X emissions. The whole area, over land and water, turns out to be in the NMVOC limited regime. Ozone scenario concentrations linearly depend on the ratio of NMVOC to NO x emissions. NO x concentrations linearly depend on changes in the total emissions of NO x and NMVOC. They are inversely related to changes in the ratio of NMVOC to NO x emissions. HNO 3 concentrations mainly depend on the total emission changes with NO x emission changes being of doubled relevance compared to NMVOC emission changes. The same relation is found for nitrogen deposition. Compared to mean ozone concentrations from the reference case, higher (lower) NO x emissions reduce (increase) ozone concentrations, while HNO 3 concentrations are increased (reduced). In contrast, reduced (increased) NMVOC emissions reduce (increase) both, ozone and HNO 3 concentrations and, in addition, the nitrogen deposition.