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The impact of precise spectroscopic measurements on the P(9) multiplet in the v3 band of 12CH4, obtained using a newly developed cold Herriott cell coupled with a tunable diode laser spectrometer, is examined in the context of remote sensing of methane in the atmosphere. More specifically, the influence of the air-broadening temperature dependence, of line narrowing and of line-mixing effects is assessed when fitting high resolution atmospheric spectra recorded from a balloon in the solar occultation mode. This is achieved by considering residuals and retrieved methane volume mixing ratio profiles. By combining data from previous studies together with new measurements, the expression for the temperature dependence of the broadening coefficient has been revisited. It is shown that a correcting factor applied to the usual law gives better results, when considering all the available measurements from room temperature down to about 10-20 K, as compared to the usual expression of the width versus temperature. These results clearly demonstrate that collision broadening is more sensitive to long-range attractive forces when the temperature is decreased.

We describe the updates to the spectroscopic parameters of ozone and its isotopes in the 1996 HITRAN compilation. Recent published studies not included in HITRAN are also summarized. Finally, we report the identification of infrared lines of the v(sub 3) bands of O-16O-16O-17 and O-16O-17O-16 in high-resolution solar spectra recorded by stratospheric balloon-borne and ground-based Fourier transform spectrometers.

The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.

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.

High-resolution Fourier transform spectra covering the 720-9-10/ cm spectral region have been used to perform a reanalysis of the 2nu(sub 2) band ((010) - (000) vibrational transition) together with the first analysis of the nu(sub 2) - nu(sub 2) hot band of nitrogen dioxide ((020)-(010) vibrational transition). The high-quality spectra show that, for numerous nu(sub 2) lines, the hyperfine structure is easily observable in the case of resonances due to the hyperfine Fermi-type operator. By performing a full treatment of the spin-rotation and of the hyperfine operators, a near line list of the nu(sub 2) band (positions and intensities) has been generated, and it is in excellent agreement with the experimental spectrum. Also, a thorough analysis of the -2nu(sub 2) nu(sub 2) hot band has been performed leading to an extended set of new (020) spin-rotation levels, These levels, together with the (100), (020), (001) spin-rotation levels deduced previously from the analysis of thenu(sub 1), 2nu(sub 2), and nu(sub 3) cold bands performed in the 6.3 - to 7.5 microns spectral range were least-squares fitted, allowing one to derive a new set of vibrational band centers and rotational. spin-rotation, and interaction constants for the {(100)(020)(001)} interacting states of N-14(16)O2.

Stratospheric volume mixing ratio profiles of N2O5, CH4, and N2O have been retrieved from a set of 0.052/cm resolution (FWHM) solar occultation spectra recorded at sunrise during a balloon flight from Aire sur l'Adour, France (44 N latitude) on 12 October 1990. The N2O5 results have been derived from measurements of the integrated absorption by the 1246/cm band. Assuming a total intensity of 4.32 x 10 exp -17 cm/molecule/sq cm independent of temperature, the retrieved N2O5 volume mixing ratios in ppbv, interpolated to 2 km height spacings, are 1.64 +/- 0.49 at 37.5 km, 1.92 +/- 0.56 at 35.5 km, 2.06 +/- 0.47 at 33.5 km, 1.95 +/- 0.42 at 31.5 km, 1.60 +/- 0.33 at 29.5 km, 1.26 +/- 0.28 at 27.5 km, and 0.85 +/- 0.20 at 25.5 km. Error bars indicate the estimated 1-sigma uncertainty including the error in the total band intensity. The retrieved profiles are compared with previous measurements and photochemical model results.

Recently available spectral O3 line parameters are summarized and progress in remote sensing based on these parameters is discussed. Particular attention is given to covering line positions, line intensities and linewidths for both the main isotopic species (O-16)3 and the isotopic variants (O-16)(O-18)(O-16) and (O-16)(O-16)(O-18).

We describe in this paper the modifications, improvements, and enhancements to the HITRAN molecular absorption database that have occurred in the two editions of 1991 and 1992. The current database includes line parameters for 31 species and their isotopomers that are significant for terrestrial atmospheric studies. This line-by-line portion of HITRAN presently contains about 709,000 transitions between 0 and 23,000/cm and contains three molecules not present in earlier versions: COF2, SF6, and H2S. The HITRAN compilation has substantially more information on chlorofluorocarbons and other molecular species that exhibit dense spectra which are not amenable to line-by-line representation. The user access of the database has been advanced, and new media forms are now available for use on personal computers.

Very-high-resolution FWHM solar-occultation spectra are investigated with a balloon-borne interferometer using revised spectroscopic line parameters for HNO3, O3, and H2O. The O3 and H2O data are evaluated to determine their capacity for interference in the HNO3 line which is studied in the nu sub 2 band at 5.8 microns. The line parameters developed with the stratospheric data are compared to data based on a HITRAN compilation as well as laboratory spectra with a 0.002/cm resolution. The line list is calculated and shown to include J and Ka transitions which improve the line parameters for HNO3 by accounting for the weaker absorption features in the stratospheric spectra. The stratospheric HNO3 profile developed analytically is compared to those based on reported measurements, and the one developed with the stratospheric solar spectra is found to be consistent with the measurements and confirm inherent measurement biases.

Spectra of (O-16)3 at 1800-5400/cm, obtained at resolution 0.01/cm using the Fourier-transform spectrometer of the National Solar Observatory at Kitt Peak, are presented and analyzed; the focus is on the nu2+2nu3, nu1+nu2+nu3, and 2nu1+nu2 bands. The experimental and data-analysis procedures employed are those described by Flaud et al. (1987 and 1989), Malathy Devi et al. (1987), and Rinsland et al. (1988). The vibrational and rotational constants for the (012), (111), and (210) states are listed in a table, and the nu0 band centers for these states are given as 2726.1066/cm, 2785.2391/cm, and 2886.1781/cm, respectively.

The objective of this program is to obtain data concerning the concentration versus altitude of various constituents of interest in the photochemistry of the stratospheric ozone layer. Data pertinent to this objective are obtained using balloon-borne instruments to measure the atmospheric transmission and emission in the mid infrared. In addition to obtaining constituent profile information, the spectral data obtained are also used to identify absorption or emission features which may interfere with the retrieval of constituent data from satellite instruments using lower spectral resolution. The spectral resolution obtained with the solar spectral system is 0.0025 cm(exp -1) and represents about a factor of 5 greater resolution than any solar spectra previously obtained in this spectral region. As a result of the increase in spectral resolution, a large number of features are observed in these spectra which were not observed in previous studies. Identification and analysis of these features is in progress. The results of this analysis to date shows a number of HNO3 features which have not been observed before, and these occur where they will interfere with the retrieval of other constituents. An example of the interference is the occurrence of features in the 780.2 cm(exp -1) region which overlap the ClONO2 feature which will be used for retrieval of ClONO2 by the CLAES instrument on UARS. A number of features due to COF2 were also identified in the 1250 cm(exp -1) region which may interfere with retrieval of N2O5.

Fourier transform spectra of ozone have been recorded in the 2-5-micron region at a resolution of 0.01/cm. Absorption lines belonging to numerous vibration-rotation transitions have been observed in these spectra, and a detailed analysis of the band system centered at 3.6 microns has been completed.

During the period of Feb. 28 to Mar. 2, 1986, 19 high resolution atmospheric spectra have been recorded during the night using the moon or during the day using the sun as a source with the Fourier transform spectrometer at the McMath Solar telescope on Kitt Peak. The NO2 absorption peak located at 2914.65/cm has been used to derive from the spectra the total vertical column densities of atmospheric NO2. A rather rapid decrease of the NO2 amount during the night has been observed, and its daytime increase from sunrise to sunset has been confirmed. A comparison with the predictions of a photochemical model is given.

Using 0.005/cm-resolution Fourier transform spectra of samples of ozone, the gamma 1 and gamma 3 bands of (16)O3 have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K sub a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the gamma 1 and gamma 3 states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the gamma 1 and gamma 3 bands of (16)O3 has been generated.

The latest edition of the AFGL atmospheric absorption line parameters compilation for the seven most active infrared terrestrial absorbers is described. Major modifications to the atlas for this edition include updating of water-vapor parameters from 0 to 4300 per cm, improvements to line positions for carbon dioxide, substantial modifications to the ozone bands in the middle to far infrared, and improvements to the 7- and 2.3-micron bands of methane. The atlas now contains about 181,000 rotation and vibration-rotation transitions between 0 and 17,900 per cm. The sources of the absorption parameters are summarized.