The foreign-continuum absorption of water vapour in the far-infrared (50–500 cm−1). (March 2021)

• Record Type: Journal Article
• Authors: Koroleva, Aleksandra O.; Odintsova, Tatyana A.; Tretyakov, Mikhail Yu.; Pirali, Olivier; Campargue, Alain
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 261(2021)
• Publication Date: 2021-03
• Subjects: Water vapour -- Rotational spectrum -- In-band continuum -- Bimolecular absorption -- Terahertz gap -- Synchrotron; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2020.107486
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: H2 O foreign-continuum absorption is retrieved at 296 K in the 50-500 cm −1 range. First laboratory measurements in the wide 90-330 cm −1 interval including the range of maximum intensity of H2 O pure rotational band. Expected pressure dependences of the continuum are verified. The foreign-continuum cross-sections for O2, N2 and dry air are derived separately and used for data validation. Abstract: We investigated the continuum absorption of water vapour diluted in nitrogen, oxygen and air in the range of the pure rotational band of the water molecule (50-500 cm −1 ). Spectra recordings were performed at room temperature with a Fourier transform spectrometer associated to a 151-m multipass gas cell located at the AILES beamline of SOLEIL synchrotron facility. The study includes the first laboratory measurements in the wide 90-330 cm −1 interval. Tests of the baseline stability, crucial for the continuum determination, are reported together with the expected pressure dependences of the continuum absorption, measured over different pressure ramps. Retrieved foreign-continuum cross-sections are found in good agreement with literature values available in the lower and upper parts of the studied frequency range. The reported results validate the MT_CKD foreign-continuum empirical model, widely used in atmospheric applications, even if some overestimation of the MT_CKD values is noted in the centre of the band where experimental data were absent. Graphical abstract: Image, graphical abstract