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.

Infrared measurements of atmospheric gases above Mauna Loa, Hawaii, in February 1987

“…6. Although the measured HCl total column is about a factor of 2 higher than aircraft total column measurements obtained near the same latitude 9 years earlier by Mankin and Coffey [1983], discrepancies between these aircraft values and the higher aircraft values reported by Girard et al [1982Girard et al [ , 1983 and the absence of measurements to assess the concentrations of HC1 in the troposphere above Mauna Loa make it impossible at present to derive information about long-term trends in the HC1 total column from our data. 7.…”

“…Our results therefore provide benchmark observations of the total burdens of a number of gases above this site. For gases concentrated primarily in the stratosphere (e.g., HC1 and HNO3) , our measured total columns can be compared with values from airborne latitudinal surveys [e.g., Mankin and Coffey, 1983;Girard et al, 1982Girard et al, , 1983]. Our measured ozone total column can be directly compared with correlative Mauna Loa Dobson results.…”

Composition measurements of the 1989 Arctic winter stratosphere by airborne infrared solar absorption spectroscopy

“…The 1987 Antarctic measurements were all made inside the vortex, and so a single set of vmr profiles was adopted for the entire mission. This profile set was determined from spectra measured at three different solar zenith angles on the same day (September 24, 1987) in the same location using the method described by Girard et al [1983]. In the 1989 AASE campaign the observations frequently straddled the edge of the vortex, and so it is unreasonable to reduce all of the data using a single set of vmrs.…”

Concentrations of carbonyl sulfide and hydrogen cyanide in the free upper troposphere and lower stratosphere deduced from ATMOS/Spacelab 3 infrared solar occultation spectra

“…Both results support the idea that the OCS volume mixing ratio between sea level (see range indicated by the horizontal arrows) and the tropopause remains relatively constant. The airplane results fromGirard et al [1983]results for 28øN, but it appears much too high above that altitude. Parameters such as the OH concentration versus altitude, the eddy diffusion coefficients, the temperature dependence of the rate coefficient of the reaction OCS + OH[Turco et al, 1981], and the tropopause height need to be better evaluated through field and laboratory investigations.…”