Latitudinal distribution of ten stratospheric species deduced from simultaneous spectroscopic measurements

Abstract

Solar infrared absorption spectra have been recorded from an aircraft during nine flights, in April–May 1980, at various latitudes between 62° north and 60° south. Using a solar occultation technique, the instrument is a spectrometer associated with a heliostat and designed for scanning automatically, in a repetitive sequency of measurements, a set of selected narrow spectral intervals within the spectral range 1000 to 4000 cm−1. Simultaneous measurements are presented concerning NO2, COS, H2O, CH4, N2O, O3, CO, HNO3, HF, and HCl. The results deduced from observations are the vertical column density above the flight altitude, near 11.5 km, the local concentration at the flight altitude, and qualitative information about the stratospheric vertical profile. A similar variation is observed for HNO3, HCl, and HF: for these three species, the vertical column density increases from the equator to the polar region in both hemispheres. The CO vertical column density decreases by a factor of 4 from the equator to high latitude in both hemispheres, with values slightly larger in the northern equatorial region than in the southern hemisphere at the same latitude. The latitudinal variation of H2O vertical column density is discussed in relation to the tropopause height. Some similarities are observed for latitudinal and seasonal variations of nitrogen dioxide and ozone.