In situ aircraft measurements of NO, NO_y, CO and O_3 in the free troposphere between 60 N and 60 S North-South contrast and distribution in the tropics / Flugzeugmessungen von NO, NO_y, CO und O_3 in der freien Troposphaere zwischen 60 N und 60 S Nord-Sued-Kontrast und Verteilung in den Tropen

In situ aircraft measurements of NO, NO_y, CO and O_3 performed on board the DLR research aircraft Falcon are used to examine the interhemispheric differences for midlatitudes during local autumn. The observations were part of the INCA-campaign (Interhemispheric differences in cirrus properties due to anthropogenic emissions). Mayor deployment sites were Punta Arenas, Chile (53 S) and Prestwick, Scotland (55 N). Median mixing ratios of NO, NO_y, CO and O_3 in the upper troposphere in the investigation area near Prestwick exceed the observed concentrations in Punta Arenas by factors of 4.5, 3, 1.5 and 1.2, respectively, due to the influence of convective vertical transport of polluted boundary layer air and aircraft emissions. For northern midlatitudes a significant ozone production was calculated, in contrast to the middle troposphere over Punta Arenas where ozone destruction was inferred due to the very low NO-levels observed there. The measurements were compared to simulations of two chemistry transport models. In addition, the meridional distribution of the trace gases measured during the transfer flights from Germany to Chile and back were analysed for latitudes between 60 N and 60 S. For the upper troposphere over tropical South America strongly enhanced CO- and NO_y-concentrations were observed. These air masses encountered deep convection over the Amazon basin and are distributed over a large area due to an upper level anticyclonic flow over South America, typical for the wet season. (orig.) / SIGLE / Available from TIB Hannover: RN 437(04-01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek / DE / Germany