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Atmospheric and laboratory atlases of high-resolution infrared absorption spectra have been generated from data obtained with the University of Denver Michelson-type interferometer balloon-borne spectrometer systems. The main objectives of the atlas work have been the identification and the detailed analysis of stratospheric infrared high-resolution spectral features. The stratospheric atlases cover many spectral intervals and provide tables of line positions and species identifications. High Sun spectra are used for identification of solar lines. Latest editions of these atlases include selected sections in the 760-1950- and 800-1700-cm(-1) regions at 0.02- and 0.002-cm(-1) resolutions, respectively. In addition to the stratospheric atlases, ground-based and laboratory spectral atlases have also been produced. The laboratory spectra of many molecules relevant to stratospheric chemistry have been obtained. A number of ongoing spectroscopic studies have been developed on the basis of the atlas work, including studies of solar and atmospheric spectral features.

A mid IR Michelson interferometer capable of obtaining 0.002-cm(-1) resolution solar spectra has been developed for balloon use. The interferometer is based on the Bomem self-aligning instrument, and is equipped with a solar tracking system, telemetry, and recording systems, as well as temperature control and gondola orientation. The interferometer has made two successful flights in the 7-14 microm (700-1300-cm(-1)) interval up to 40 km. The basic systems are described and sample spectra are presented.

High-resolution ground-based solar spectra recorded at the Amundsen-Scott South Pole station in Dec. 1980 and Nov. 1986 have been analyzed in the region of the CF(2)Cl(2) (chlorofluorocarbon 12) nu(8) band Q branches at 1161 cm(-1). An increase in the CF(2)Cl(2) total vertical column above the South Pole of 1.24 +/- 0.15 over the 6-yr period, corresponding to an average rate of increase of 3.6 +/- 2.1%, is derived. This rate of increase is lower than indicated by in situ measurements at the South Pole over the same time period, but there is agreement when the rather error bars of the spectral measurement results are considered. Spectroscopic parameters that can successfully model CF(2)C1(2) absorption at low temperatures are needed to improve retrieval accuracies and could be applied to a number of pre-1980 atmospheric spectral data sets in the literature to obtain an improved record of early CF(2)Cl(2) concentration trends for comparison with estimates of historical release rates.

A set of stratospheric aerosol optical models is employed in a radiative-transfer computation to study the effects of postvolcanic particle size distributions and compositions on the spectral radiance in the 8-13-microm window region. The models are based on direct measurements of post El Chichon aerosol size distributions and vertical profiles. They represent various maturity states of aerosols composed of sulfuric acid aqueous solutions, formed and evolved in the stratosphere following a massive volcanic eruption. Comparisons are made with concurrent radiance observations obtained on balloon flights 6 months after the eruption and 1 yr later. Most of the calculations are done using the LOWTRAN-6 code (either alone or combined with a multiple scattering calculation), revised so as to include the appropriate aerosol optical models. A better quantitative agreement is found between the calculated and observed spectral radiances when the aerosol loading is relatively high, indicating that additional minor radiance sources of a yet unresolved nature should be incorporated in the present version of the calculation.

A frost point hygrometer designed for aircraft operation was included in the complement of instruments assembled for the NASA U-2 flights through the plume of Mount St. Helens. Measurements made on the 22 May flight showed the water vapor to be closely associated with the aerosol plume. The water vapor mixing ratio by mass in the plume was as high as 40 x 10(-6). This compares with values of 2 x 10(-6) to 3 x 10(-6) outside of the plume.

In April 1979, measurements of nitrogen dioxide in the upper atmosphere were made near Soufriere Volcano by twilight optical-absorption techniques. The derived value of 5 x 10(15) molecules per square centimeter column implies an enhancement of 25 percent over earlier abundances measured in the same latitudinal regions. This enhancement may represent the normal stratospheric variability of nitrogen dioxide in the equatorial region but in any case may be considered an upper limit to the volcano's effect on the total nitrogen dioxide abundance.

A nonlinear least-squares fitting procedure has been used to derive the stratospheric N(2)O mixing ratio profile from balloon-borne solar absorption spectra and laboratory spectra near 1880 cm(-1). The atmospheric spectra were recorded during sunset from a float altitude of 33 km with the University of Denver 0.02-cm(-1) resolution interferometer near Alamogordo, N.M. (33 degrees N), on 10 Oct. 1979. The laboratory data were used to determine the N(2)O line intensities. The measurements indicate an N(2)O mixing ratio of 264 ppbv near 15 km decreasing to 155 ppbv near 28 km.

High resolution solar spectra at high and low sun angles in the 3200-3400-A region were obtained during balloon flights on 9 Feb. 1977 (altitude 41 km) and 17 Feb. 1977 (altitude 29 km). These data were analyzed using a layer-by-layer three-wavelength differential absorption method. Ozone volume-mixing ratio profiles, which agree with standard profiles, were derived. Suggestions are made for improving the accuracy of the results in future measurements.

Quantitative measurements were made in the 1700-2636-A wavelength interval at 22 degrees C of the pure HNO(3) vapor absorption spectrum. Absorption coefficients, which were found to be both pressure and length dependent, were determined using six absorption cell lengths between 0.1 cm and 10.0 cm, and numerous gas pressures in the 0.0004-0.066-atm range. The statistical spectral band model with a Voigt line profile was applied to the data and the band model parameters were derived. The results were used to estimate the absorption of uv radiation by stratospheric HNO(3).

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.

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.

A balloon-borne spectrometer was used to measure the atmospheric absorption of solar radiation in the 9-10-micro region as a function of altitude. Among the numerous spectra recorded, several were made with very long optical paths above the troposphere obtained from floating altitude (~30 km) while the sun set. When the experimental results are compared with calculated spectra, based on line by line parameters of the nu(3) and nu(1) fundamentals of ordinary ozone, (16)O(3), combined with the Curtis-Godson approximation, large discrepancies are found for the long path spectra. It is shown that the hot bands nu(3), + nu(2), - nu(2), and nu(3), + nu(3), - nu(3), of the (16)O(3), and the nu(3) fundamentals of the isotopic species (16)O(18)O(16)O and (16)O(16)O(18)O, can contribute significant absorption for long paths such as obtained in this experiment. Such long paths also give rise to significant absorptions by the nu(3) - nu(1) and the nu(3) - 2nu(2) degrees bands of CO(2). Including these weak bands in the calculated spectra leads to good agreement with the observed data.

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.