Measurements of water vapor total content in the solar spectrum of the atmosphere

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   Registration of absorption spectra of solar radiation, passed through the
   the Earth's atmosphere, was carried out by the Fourier spectrometer
   IFS-125M. All spectra were recorded during the period of May 17-23, 2012.
   Conditions of spectrum registration: spectral range is 25,000 - 8000 cm^-1
    (400 - 1250 nm); photodetector is silicon photodiode; the
   splitter is quartz; resolution is 0.05 cm^-1; scanner speed is 20
   kHz; the diameter of the aperture is 0.6 mm; time of one measurement is 10
   minutes. The measurements were carried out with the diameter of the
   aperture of 0.85 mm (in this case, the signal to noise ratio (S/N) is
   increased by 2-3 times), however, spectrum distortion was observed in the
   high-frequency range of 400-500 nm. In the area of 18000 cm^-1   S/N = 100.

  Spectrum registration during the mentioned period was carried
   out from 8-30 till 18-00. During the experiment, solar radiation was often
   covered by clouds. The results, obtained during the measurements, were
   processed by SFIT v3.92 program . In the result, the data on water vapor
   total content were obtained during the processing of experimental data in
   the range of 9900-10000 cm^-1. Some intervals were selected:
   9979.4-9981.15 cm^-1 and 9941-9958 cm^-1 - in this case,
   the results of calculations of water vapor total content were the most
   stable.
  

   Н₂О total content = 4.28х10²² mol/cm²
  

   Measurements of the Fourier-spectrometer were compared with the
   measurements of sun photometer. The difference with the first range
   (9979.4-9981.15 cm^-1) was 1.2 percent.
   The work is partly supported by the Rusian Fund for Basic Research Grants,
   RAS Program 3.9.