Model analysis of the measured concentration of organic gases in the Norwegian Arctic

A 2-D meridional model for the chemistry and transport in the troposphere is used to study the seasonal variation of the concentration of organic gases like C₂H₂, C₂H₆, C₃H₈, C₆H₆, C₇H₈. CHCl₃ and C₂Cl₄ at high latitudes. The anthropogenic sources for these species were estimated, and the temporal and latitudinal distribution of OH and O₃ was calculated using a complex photochemical reaction system. There is fair agreement between the calculated annual variation and the measured concentrations for C₂H₂, C₂H₆, C₃H₈, C₇H₈ and C₂Cl₄ at Spitsbergen during July 1982 and March/April 1983, with a distinct late winter maximum and summer minimum. For CHCl₃, the direct anthropogenic source is minor compared to indirect anthropogenic or natural sources. For benzene, emission in car exhaust is important, but other anthropogenic sources are required for the calculations to agree with the measurements. Measured C₂H₄ and C₃H₆ concentrations are much higher than the calculated ones based on anthropogenic emissions, and show opposite seasonal trends. This indicates biogenic sources for these compounds.A buildup of PAN (300 pptv) is calculated at high latitudes during winter. This makes it the dominant source for NO_x as the temperature increases in the spring. NO_x is found to be a limiting factor for O₃ production at high latitudes during spring.