The absorption spectra of the mixtures of water vapor and air at different partial pressures of both gases have been recorded using a Fourier spectrometer IFS 125 HR in the 3500−5670 cm–1 spectral region. The multispectrum fitting procedure has been applied to these spectra to recover the spectral line parameters. The traditional Voigt and quadratic speed-dependent Voigt ones were used. Particular attention was paid to the analysis of the broadening and shift coefficients of the H2O absorption lines. The significant difference between the obtained and literary data was shown. The atmospheric transmission was simulated with the H2O absorption lines from the HITRAN and GEISA spectroscopic databases and with new lines parameters obtained in this work.
Atmospheric monitoring of methane shows that CH4 concentration growth since 2007 is accompanied by C13/C12 isotopic delta ratio shift to more negative values due to 13CH4 content depletion. In the work, the atmospheric total column amount and vertical profiles of 13CH4 and 12CH4 are retrieved from the ground-based measurements of solar spectra in Kourovka observatory. The CH4 isotopologues ratio is calculated. The error of the isotopologues content retrieval is estimated for different spectral regions. On basis of the obtained results, optimal spectral windows were found.
The atmospheric transmission of UV radiation was simulated with use of new data on H2O absorption lines in the 0.25- 0.4 μm spectral region. The transmittance spectra were calculated with the most complete H2O line list POKAZATEL, its new modification in 2020 by Conway et al, refined databank W2020, and new version of popular spectroscopic database HITRAN2020, in which the H2O lines were added in the UV region. The intercomparison of the spectra was made. The water vapor contribution to the atmospheric transfer of solar radiation in the UV region was estimated. The radiative transfer was modeled with taking into account of aerosol and Rayleigh multiple scattering and absorption.
Estimation of contribution of new theoretical lines of water vapor monomer from the POKAZATEL calculations to the absorption of solar radiation in the UV spectral region is made. The atmospheric transmission is calculated with use of different broadening parameters of H2O absorption lines.
Water vapor is an important greenhouse gas. The atmospheric water vapor content is monitored by remote methods, which require accurate spectroscopic information about H2O absorption line parameters. The problems of accuracy of accounting the selective water vapor absorption in the simulation of atmospheric transfer of solar radiation are considered in this work. The atmospheric spectra are simulated using different versions of spectroscopic databases of H2O absorption line parameters and compared with the solar spectra measured by a ground-based Fourier transform spectrometer. The total column (TC) water vapor is retrieved from the solar spectra measured. The effect of the differences in absorption line parameters in modern spectroscopic databases on the results of retrieval of the TC water vapor from high-resolution spectra is estimated.
The atmospheric radiative fluxes and cloud radiative forcing are simulated with use of different models of water vapor continuum absorption and cloud optical depths. The effects of radiative heating and cooling of the cirrus cloudiness are analysed. A contribution of water vapor continuum absorption to the atmospheric radiative transfer is estimated. It is shown that sign of cloud radiative effect depends on choice of water vapor continuum model.
The atmospheric solar spectra are simulated using new data on methane absorption lines. A comparison of the simulated spectra with the atmospheric spectra, measured by a ground-based Fourier spectrometer in the methane absorption bands in the near-infrared spectral region, is carried out. The atmospheric column-averaged volume mixing ratio of methane is retrieved from the measured spectra.
Estimations of the effect of modern ozone absorption cros-ssections data on calculation of the atmospheric transmission and fluxes, measured using Sun photometers in the UV spectral region, are made. The ozone absorption cross-sections, often used in radiative codes, and new data of Serdyuchenko et al. are considered.
The atmospheric solar spectra are calculated using different spectroscopic databases of H2O absorption line parameters in the temperature and humidity range observed in the mid-latitudes. A comparison of the simulated spectra and measured high-resolution atmospheric spectra in the near-infrared water vapor bands, is carried out. It is shown that the values of H2O atmospheric column, retrieved using different modern spectroscopic databases may vary by more than 3%.
The sulfur dioxide absorption cross sections, measured with a Fourier transform spectrometer at room temperature and varied pressure of SO2-N2 in the 260-330 μm region, are presented. The absorption spectra are obtained at a high spectral resolution of 0.5 cm-1. The measurements results are compared with SO2 cross section data from literature.
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