Global modeling of the nitrate radical (NO3) for present and pre-industrial scenarios

• Published in: Atmospheric research Vol. 164-165; pp. 347 - 357
• Main Authors: Khan, M.A.H., Cooke, M.C., Utembe, S.R., Archibald, A.T., Derwent, R.G., Xiao, P., Percival, C.J., Jenkin, M.E., Morris, W.C., Shallcross, D.E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2015
• Subjects: HOx recycling; NO3; Pre-industrial scenario; Present scenario; STOCHEM-CRI; Present scenario; NO3; STOCHEM-CRI; HOx recycling; Pre-industrial scenario
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2015.06.006

Increasing the complexity of the chemistry scheme in the global chemistry transport model STOCHEM to STOCHEM-CRI (Utembe et al., 2010) leads to an increase in NOx as well as ozone resulting in higher NO3 production over forested regions and regions impacted by anthropogenic emission. Peak NO3 is located over the continents near NOx emission sources. NO3 is formed in the main by the reaction of NO2 with O3, and the significant losses of NO3 are due to the photolysis and the reactions with NO and VOCs. Isoprene is an important biogenic VOC, and the possibility of HOx recycling via isoprene chemistry and other mechanisms such as the reaction of RO2 with HO2 has been investigated previously (Archibald et al., 2010a). The importance of including HOx recycling processes on the global budget of NO3 for present and pre-industrial scenarios has been studied using STOCHEM-CRI, and the results are compared. The large increase (up to 60% for present and up to 80% for pre-industrial) in NO3 is driven by the reduced lifetime of emitted VOCs because of the increase in the HOx concentration. The maximum concentration changes (up to 15ppt) for NO3 from pre-industrial to present day are found at the surface between 30oN and 60oN because of the increase in NOx concentrations in the present day integrations. •Peak NO3 is found over the continents near NOx emission sources.•Regionally, NO3 is formed by the reaction of NO2 with O3.•Including of HOx recycling results in an increase of up to 60% NO3 over tropics.•NO3 level increases (up to 15ppt) from pre-industrial to present scenarios.