Measurements of selected C2-C5 hydrocarbons in the background troposphere: Vertical and latitudinal variations

Meridional cross sections of the concentration of light hydrocarbons are reported. They were obtained from 20. April to 10. May, 1980, during the French research flight STRATOZ II, and cover the latitudes between 60° N and 60° S and the altitudes between 800 mb and 200 mb. The mixing ratios of ethane, ethene, acetylene, propane, propene, n-butane, i-butane, n-pentane, and i-pentane range between 2.0 and 0.02 ppb. Globally, a decrease in concentration with increasing altitude and -in most cases-with decreasing latitude is observed. In addition the 2-dimensional concentration fields show structures of different scales. In particular, isolated maxima of high concentrations are found in the upper troposphere. They point to fast vertical transport between the boundary layer and the upper troposphere. In the present case these maxima seem to be correlated with large scale meteorological systems, such as low pressure regions or the Inter Tropical Convergence Zone. It is argued that the NMHC provide a set of tracers well suited to the detection of fast vertical transport

The Influence of Man-Made SO2 and Particle Emission on the Global Aerosol Concentration and the Optical Properties of the Atmosphere

Using a two-dimensional grid point model and zonal mean values of temperature, humidity, wind field and exchange coefficients the zonal distribution of aerosol particle concentration and SO2 concentration are calculated. This is done for the natural sources of aerosol particles, H2S and DMS and for the man-made emission of aerosol particles and SO2 as estimated for natural emission conditions, for the present man-made emission and for twice the amount of present man-made emission