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Vertical profiles of the CH4 mixing ratio in the troposphere and stratosphere were obtained by collecting air samples and analyzing their CH4 concentrations by gas chromatography. Two sets of tropospheric profiles, each covering a full year, have been measured; one over the Pacific 200 km offshore from Santa Barbara, California, and one over Scottsbluff, Nebraska. Although some of the individual profiles showed large fluctuations with time and space, a systematic seasonal variation of tropospheric CH4 concentration could not be established. On a 1-year average, CH4 has a nearly uniform distribution in the troposphere, with an average volume mixing ratio of 1.41 ppmv. The only systematic gradient in the troposphere was observed for the Scottsbluff profiles which showed a decrease in the CH4 mixing ratio close to the ground. In contrast, the stratospheric CH4 profiles showed a systematic decrease with altitude, with a steeper gradient directly above the tropopause. The gradient appears to be weaker at higher altitudes. At 50 km the CH4 mixing ratio has dropped to 0.25 ppmv.

Three millimeter-wavelength transitions of ClO were searched for in the stratospheric emission spectrum during May-August 1977 using aircraft-based instruments. The measurements indicate that if stratospheric ClO has a vertical distribution of the form predicted by present photochemical models, then the ClO volume mixing ratio at the profile peak did not exceed 10 to the -9th at the time and place of the measurements. The observed spectra suggest the presence of ClO in the stratosphere but do not provide a definitive detection.

The altitude distribution of nitric oxide was measured during three balloon flights in August 1976 and 1978. Median values of the volume mixing ratio at 18, 24, 30, and 34 km were 0.4, 1.4, 6.5, and 13 ppb, respectively. The data are discussed in relation to an average profile of nitrogen dioxide measured for this season and latitude and in relation to current one-dimensional models of the stratosphere.