Remote sensing of high temperature H 2O–CO 2–CO mixture with a correlated k-distribution fictitious gas method and the single-mixture gas assumption

• Published in: Journal of quantitative spectroscopy & radiative transfer Vol. 102; no. 2; pp. 304 - 315
• Main Authors: Caliot, C., Le Maoult, Y., El Hafi, M., Flamant, G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2006
• Subjects: Atmospheric path; Correlated k-distribution; Fictitious gas; Plume signature; Remote sensing; Single-mixture gas; Single-mixture gas; Plume signature; Atmospheric path; Correlated k-distribution; Remote sensing; Fictitious gas
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2006.02.017

Infrared spectra of high temperature H 2O–CO 2–CO mixtures are calculated using narrow band models in order to simulate hot jet signature at long distance. The correlated k-distribution with fictitious gas (CKFG) approach generally gives accurate data in such situations (especially for long atmospheric paths) but results in long computation time in cases involving mixtures of gases. This time may be reduced if the mixture is treated as a single gas (single-mixture gas assumption, SMG). Thus the lines of the single-mixture gas are assigned to the fictitious gases. In this study, the accuracy of two narrow band models is evaluated. The first narrow band model considers one single-mixture gas and no fictitious gas (CK-SMG) whereas the second model accounts for one single-mixture gas and three fictitious gases (CKFG-SMG). Both narrow band models are compared with reference spectra calculated with a line-by-line (LBL) approach. As expected, the narrow band accuracy is improved by the fictitious gas (FG) assumption particularly when long atmospheric paths are involved. Concerning the SMG assumption, it may lead to an underestimation of about 10% depending on the variation of the gas mixture composition ratio. Nevertheless, in most of realistic situations the SMG assumption results in negligible errors and may be used for remote sensing of plume signature.