Aircraft observations of NO, NOy, CO and Co3 in the upper troposphere from 50 N-60 S-Interhemspheric differences and distributions over tropical South America

Measurements of NO, NOy, CO, and O3 made in the middle and upper troposphere over Punta Arenas, Chile (53°S) and Prestwick, Scotland (55°N) during the INCA (Interhemispheric Differences in Cirrus Properties from Anthropogenic Emissions) experiment in 2000 are used to examine the interhemispheric differences in the abundance of these species during local autumn. Median mixing ratios of NO, NOy, O3, and CO in the upper troposphere (8 km-tropopause) are 4.5, 3, 1.5 and 1.2 times higher over Prestwick compared to Punta Arenas, respectively. Corresponding enhancement factors for the middle troposphere are 5, 7.8, 1.5, and 1.4. The present data represent a considerable extension of the sparse NO and NOy data so far available for the middle and upper troposphere at southern midlatitudes.