W. J. Williams

Measurements of stratospheric halocarbon distributions using infrared techniques

Absorption bands of CF2Cl2, CFCl3 and CCl4 have been observed in infrared sunset solar spectra in the 800-1000 cm−1 region from 30 km altitude during a balloon flight made in September 1975. The infrared absorption bands were used to derive the distribution of these constituents in the upper troposphere and lower stratosphere. The results are compared with 1968 data and with current results of other authors.

Presence of HNO 3 in the Upper Atmosphere

Observations of absorption of solar radiation by atmospheric nitric acid obtained on different balloon flights are presented. This absorption occurs in three different wavelength intervals. The use of the very long paths, occurring near sunset, for enhancing weak absorption is discussed.

Variation of the Infrared Solar Spectrum Between 700 cm −1 and 2240 cm −1 with Altitude

A grating spectrometer with a Ge: Cu detector was flown on three balloon flights. Spectra in the 4-14.3-micro region were obtained at various altitudes from the ground through 30 km with a resolution considerably better than that achieved in previous flights. Some of the spectra were obtained over long paths at float altitude, during the sunset. Data from these flights are presented with a discussion of the significant features of the observed absorptions. Special emphasis is put on the new features observed during the sunset.

Distribution of Nitric Acid Vapor in the Stratosphere as Determined from Infrared Atmospheric Emission Data

Abstract Infrared emission spectra were measured in the stratosphere at various altitudes and from various zenith angles by means of a balloon-borne Czerny-Turner spectrometer. The equation of radiative transfer was applied to the radiances measured at 11.2μ to yield a concentration profile of HNO3 vapor. The resulting HNO3 concentration profile was characterized by a negligible concentration below 14 km, a maximum concentration of ∼(1.5±0.5)×1010 molecules cm−3 at ∼(19±5) km, and a diminishing concentration above these altitudes.

Distribution of Water Vapor in the Stratosphere as Determined from Balloon Measurements of Atmospheric Emission Spectra in the 24–29-μm Region

The stratospheric water vapor mixing ratio altitude profile has been derived from spectral observations of the downward night emission from the pure rotation water vapor lines in the 24-29-microm region of the spectrum. The data were obtained during two balloon flights, made on 22 February 1971 and on 29 June 1971, using a balloon-borne spectral radiometer with ~2 cm(-1) resolution. The observed radiances have been fitted to line-by-line, layer-by-layer radiance calculations, from which the water vapor mixing ratio between 10 km and 30 km has been flights show a broad minimum around of 6 x 10(-7)g/g to 4 x 10(-6) g/g.

HNO3 profiles obtained during the EASOE campaign

A small cryogenically cooled spectrometer system designed to obtain atmospheric emission spectra in the 7.5 micrometer to 13.0 micrometer region was flown piggyback on 9 balloon flights from ESRANGE (67.9 deg N, 21.2 deg E) during the European Arctic Stratospheric Ozone Experiment (EASOE) campaign. Initial analysis of the spectra obtained has been concentrated on obtaining HNO3 profiles for the various flights. HNO3 profiles for 17 December 1991, 9 January 1992, 22 January 1992, 5 February 1992 and 14 March 1992 are presented.

Upper limit for stratospheric CLONO2 from balloon-borne infrared measurements

Balloon-borne infrared sunset solar spectra in the 780 cm−1 region have been used to derive upper limits for the amount of ClONO2 in the stratosphere. These upper limits for the volume mixing ratio are 4 × 10−11 to 2 × 100−9 between 15 and 30 km with an error factor of 2. These values only show that the postulate that ClONO2 is a temporary reservoir for ClO and NO2 cannot be ruled out.

A balloon-borne grating spectrometer.

A balloon-borne, 0.5-m, Czerny-Turner grating spectrometer has been designed and constructed at the University of Denver and has measured atmospheric transmittance in several spectral regions between 2 micro and 14 micro. These data have been obtained on a series of eleven balloon flights at three geographic locations over a period of thirty months. The solar pointing system, spectrometer optics, electronics and recording system are described. The preflight and flight performance of the spectrometer is discussed and sample data presented.

Absolute integrated intensity and individual line parameters for the 6·2μ band of NO2

Abstract The absolute integrated intensity of the 6·2μ band of NO 2 at 40°C was determined from quantitative spectra at ~ 10 cm −1 resolution by the spectral band model technique. A value of 1430±300 cm −2 atm −1 was obtained. Individual line parameters, positions, intensities and ground state energies were derived, and line-by-line calculations were compared with the band model results and with the quantitative spectra obtained at ~ 0·5 cm −1 resolution.

Abundance of N 2 O in the Atmosphere between 4.5 and 13.5 km

The variation with altitude of the ir solar spectrum, in the 4.5-μ region, was observed from a balloon-borne grating spectrometer. Quantitative analysis of the N2O absorption lines in this region has shown that the N2O concentration between 4.5 and 13.5 km is 0.14±04 ppm.