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Vibrational Temperatures and Radiative Cooling of the Co 2 15 Mum Bands In the Middle Atmosphere
Author(s) -
LÓPezPuertas M.,
LÓPezValverde M. A.,
Taylor F. W.
Publication year - 1992
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711850506
Subject(s) - thermosphere , mesopause , atmosphere (unit) , atmospheric sciences , radiative transfer , mesosphere , altitude (triangle) , oxygen , daytime , atomic physics , chemistry , physics , ionosphere , meteorology , stratosphere , geometry , mathematics , organic chemistry , quantum mechanics , astronomy
Altitude and latitude distributions of the populations of the bending and symmetric stretching levels of CO 2 and of the cooling rates induced by the bands originating from them in the middle atmosphere (40‐120km), have been calculated for the CIRA 1986 reference atmosphere using a non‐LTE radiative transfer model. A sensitivity study of the more uncertain parameters that strongly affect these quantities has been undertaken. These factors are the carbon dioxide and atomic oxygen volume mixing ratios, and the rate coefficient for the deactivation of the bending mode of CO 2 by atomic oxygen. the model makes use of the most recent values of these parameters: the abundances of CO 2 in the upper mesosphere and lower thermosphere as measured by, and derived from, rocket and satellite instruments; the global distribution of atomic oxygen density calculated by Rees and Fuller‐Rowell (1988) and the measurements of Thomas (1990); and the fast rate for the deactivation of CO 2 (0, v 2 , 0) by O( 3 P), recently derived by Sharma and Wintersteiner (1990). Among the most important results are the following: (i) the CO 2 15 μm fundamental band is close to LTE (T v ‐ T k ≤ 6K) up to about 100km altitude; (ii) the first and second hot bands exhibit high vibrational temperatures, especially in the daytime summer mesopause region; (iii) the cooling rates by the CO 2 15μm bands in the lower thermosphere can be very large, depending on the CO 2 abundance. Finally, our results have been compared with other recent non‐LTE models in order to quantify the effects of different radiative transfer schemes on the calculations of vibrational temperatures and cooling rates.