Analysis of water vapor absorption lines in the modern spectroscopic databases in the 16700-17000 cm-1 region
L.N. Sinitsa, T.Yu. Chesnokova
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: absorption spectrum, water vapor, spectroscopic databases, absorption line parameters, transmittance
Abstract
The validation of H2O absorption lines parameters in the modern spectroscopic databases such as HITRAN2016, HITRAN2020, GEISA2020, and W2020 database of H2O lines is carried out in the visible region 16700-17000 cm-1. The H2O transmission spectra were simulated with the spectroscopic databases and compared with laboratory spectra of pure water vapor and H2O-N2 mixture ( P = 1 atm), recorded using a Fourier spectrometer with light-emitting diodes of high luminance. The parameters of 65 H2O absorption lines from HITRAN2020 database were corrected on the basis of the measurements. The positions of 32 lines, intensities of 51 lines, and self-broadening coefficients of 10 lines were improved. The ratio of the HITRAN2020 broadening coefficients to the experimental values is close to 1, whereas the air pressure-induced line shift coefficients in the spectroscopic databases are, on average, two times higher than the experimental values, and therefore, our previously obtained experimental values of N2 pressure-induced line shift coefficients were used to simulate the transmission spectra of H2O-N2 mixture. The difference of the experimental spectra from the spectra calculated with HITRAN2016, HITRAN2020, GEISA2020, and W2020 spectroscopic databases and corrected HITRAN2020cor gives root-mean-square deviations RMS = 1.49E-4, 1.64E-4, 3.96E-4, 3.49E-4, and 1.26E-4 in the case of pure water vapor and RMS = 1.15E-4, 1.1E-4, 2.23E-4, 2.28E-4, and 0.86E-4 for H2O-N2 mixture, respectively.
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