Journal of Atmospheric Chemistry

, Volume 36, Issue 2, pp 157–230

Impact of Non-Methane Hydrocarbons on Tropospheric Chemistry and the Oxidizing Power of the Global Troposphere: 3-Dimensional Modelling Results

  • Nathalie Poisson
  • Maria Kanakidou
  • Paul J. Crutzen
Article

DOI: 10.1023/A:1006300616544

Cite this article as:
Poisson, N., Kanakidou, M. & Crutzen, P.J. Journal of Atmospheric Chemistry (2000) 36: 157. doi:10.1023/A:1006300616544

Abstract

The impact of natural and anthropogenicnon-methane hydrocarbons (NMHC) on troposphericchemistry is investigated with the global,three-dimensional chemistry-transport model MOGUNTIA.This meteorologically simplified model allows theinclusion of a rather detailed scheme to describeNMHC oxidation chemistry. Comparing model resultscalculated with and without NMHC oxidation chemistryindicates that NMHC oxidation adds 40–60% to surfacecarbon monoxide (CO) levels over the continents andslightly less over the oceans. Free tropospheric COlevels increase by 30–60%. The overall yield of COfrom the NMHC mixture considered is calculated to beabout 0.4 CO per C atom. Organic nitrate formationduring NMHC oxidation, and their transport anddecomposition affect the global distribution of NOxand thereby O3 production. The impact of theshort-lived NMHC extends over the entire tropospheredue to the formation of longer-lived intermediateslike CO, and various carbonyl and carboxyl compounds.NMHC oxidation almost doubles the net photochemicalproduction of O3 in the troposphere and leads to20–80% higher O3 concentration inNOx-rich boundarylayers, with highest increases over and downwind ofthe industrial and biomass burning regions. Anincrease by 20–30% is calculated for the remotemarine atmosphere. At higher altitudes, smaller, butstill significant increases, in O3 concentrationsbetween 10 and 60% are calculated, maximizing in thetropics. NO from lightning also enhances the netchemical production of O3 by about 30%, leading to asimilar increase in the global mean OH radicalconcentration. NMHC oxidation decreases the OH radicalconcentrations in the continental boundary layer withlarge NMHC emissions by up to 20–60%. In the marineboundary layer (MBL) OH levels can increase in someregions by 10–20% depending on season and NOxlevels.However, in most of the MBL OH will decrease by10–20% due to the increase in CO levels by NMHCoxidation chemistry. The large decreases especiallyover the continents strongly reduce the markedcontrasts in OHconcentrations between land and oceanwhich are calculated when only the backgroundchemistry is considered. In the middle troposphere, OHconcentrations are reduced by about 15%, although dueto the growth in CO. The overall effect of thesechanges on the tropospheric lifetime of CH4 is a 15%increase from 6.5 to 7.4 years. Biogenic hydrocarbonsdominate the impact of NMHC on global troposphericchemistry. Convection of hydrocarbon oxidationproducts: hydrogen peroxides and carbonyl compounds,especially acetone, is the main source of HOx in theupper troposphere. Convective transport and additionof NO from lightning are important for the O3 budgetin the free troposphere.

non-methane hydrocarbonsozoneHOxCONOxtropospheric chemistryglobal3-d modelingupper troposphere

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Nathalie Poisson
    • 1
  • Maria Kanakidou
    • 2
  • Paul J. Crutzen
    • 3
  1. 1.Unité Mixte CNRS-CEALaboratoire des Sciences du Climat et de l'EnvironnementGif-sur-Yvette CedexFrance
  2. 2.Department of Chemistry, Environmental Chemical Processes LaboratoryUniversity of CreteHeraklionGreece
  3. 3.Division of Atmospheric ChemistryMax-Planck Institute for ChemistryMainzGermany