Features of the water vapour continuum absorption in 0.94 and 1.13 Ојm bands
A.A. Simonova1,2, R. McPheat3, I.V. Ptashnik1, K. Smith3, K. Shine4
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
2National Research Tomsk State University, 36, Lenin Avenue, Tomsk, 634050,Russia
3RAL Space, Didcot, OX11 0QX, United Kingdom
4Department of Meteorology, University of Reading, Earley Gate, PO Box 243, Reading, RG6 6BB, United Kingdom
Keywords: континуальное поглощение, водяной пар, полосы поглощения, модель континуума MT_CKD, continuum absorption, water vapour, absorption bands, MT_CKD continuum model
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.
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