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A new calculation of the radiative cooling by carbon dioxide in the middle atmosphere and the lower thermosphere

Thesis/Dissertation ·
OSTI ID:6418982
A description of an improved non-LTE model together with earlier two-level and multi-level models is presented. Effects of collisional and radiative energy transfer paths among CO2 vibrational levels on source functions are discussed. The 10 micron bands, which were previously neglected, are considered. A line-by-line calculation of transmission functions with Voigt line shape is tested and employed for evaluation of the mean specific intensity and flux divergence for a vibrational band. The cooling rate from the atmospheric carbon dioxide is evaluated for altitudes ranging from 40 to 140 km. Above 105 km, departures of source functions for the 15 micron fundamental and hot bands from LTE are so significant that non-LTE effects on band strength and transmission function cannot be neglected. The non-LTE effects increase the cooling rate for the 15 micron fundamental band, but decrease the cooling rates for the hot bands. Contributions to the total cooling rate from the hot bands for the 40 to 75 km range are comparable to the contribution from the fundamental band. Above 110 km, the hot and 4.3 micron bands make considerable contributions to the cooling, but cooling from the 10 micron band is negligible. However, the 10 micron band contribution would be significant if the non-LTE effects on the band strength and transmission function were neglected. Cooling rates of minor isotopic species are small, but are not negligible.
Research Organization:
Michigan Univ., Ann Arbor, MI (USA)
OSTI ID:
6418982
Country of Publication:
United States
Language:
English