Large Scale Distributions of O3, CO and CH4 in the Troposphere from Scientific Aircraft Measurements (Stratoz III)

Abstract

During the STRATOZ III experiment (June 1984) aimed to study some minor air constituents, continuous O3, CO and CH4 measurements were made during a series of flights aboard a “Caravelle 116” scientific aircraft, along meridional tracks between Greenland and Patagonia. The tropospheric contents are found significantly higher in the northern hemisphere than in the southern one, and reflects: (1) for O3, an important photochemical formation from anthropogenic pollution of industrialized areas (North America; Europe) at this period of the year; (2) for CO and CH4, the meridional distribution of their sources and the influence of tropospheric photochemistry. Except for West Africa, the tropical area constitutes an important sink for tropospheric ozone (photochemical losses and air ascents). A prominent CO difference between the two hemispheres is observed in the continental air, while the oceanic air is much more homogeneous. In the case of CH4, the decrease from the north to the south is regular, but the results indicate the existence of important natural sources in the southern hemisphere (Amazonia; South Pacific).