Vol. 28, issue 10, article # 1

Abstract:

The water vapour continuum absorption (or continuum) has a special importance for radiation balance of the Earth. In this paper one of the poorly studied spectral regions of the continuum absorption 8500–12500 cm^–1 (1.17–0.8 μm) is investigated, focusing on two absorption bands of water vapour. The continuum was derived from experimental pure water vapour absorption spectra obtained using a high resolution Fourier transform spectrometer. Measurements were carried out at elevated temperatures (from 398 to 471 K) and pressures (from 1 to 5 atm). Well-pronounced spectral absorption peaks were found within absorption bands, that are absent in the widely used MT_CKD model. Estimation of the total dimerization equilibrium constant for stable and metastable dimers, derived by fitting a simulated water dimer spectrum to the experimental continuum at 400 K, amounted of 0.028 atm^–1, which is twice higher than the modern ab initio prediction of this value.

Keywords:

continuum absorption, water vapour, absorption bands, MT_CKD continuum model

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