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Improved estimation of the infrared CO2 band cooling rate in the lower thermosphere due to E-V energy transfer from O(1D)
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Paper Abstract

A mechanism of excitation of the CO2 vibrational states due to E-V energy transfer through a chain O(1D) → (N2(v), v=1−5 and O2(v), v=1−4) ↔ CO2(v3) was updated in the non-LTE model for the CO2 infrared emissions in the Earth atmosphere. It was found that including this mechanism results in significant increase of populating the excited vibrational states of N2, O2 and CO2 followed by significant increase of cooling rate due to transfer of radiation in the CO2 bands in the altitude region of 90-110 km. Main inferences are as follows. For noon conditions at the equator for spring equinox under average level of solar activity (F10.7=90), about 23-25 per cent of flux of solar UV energy, which spent to excitation the O(1D) state after photodissociation of ozone and molecular oxygen, transfers to both N2(v) and O2(v) vibrational states due to E-V energy exchange during collisions. After that, a part of this flux transfers to the CO2(v3) states due to intermolecular V-V energy exchange. Finally, the energy is radiated from the atmosphere mainly in the 4.3μm fundamental band of the CO2 principal isotope with an efficiency of 0.9, 0.87, 0.82, 0.6, and 0.25 at the altitudes of 90, 95, 100, 105, and 110 km, respectively. This provides an additional cooling of the MLT region with a maximum rate of order 6.0 K/day at 105 km. Such an estimation is more larger than it had been obtained in previous investigations. So, comparing to the most recent estimations of the 15 μm CO2 band cooling rate, this seems to be a valuable additional source of cooling of the lower thermosphere comparing to the most recent estimations of the 15 μm CO2 band cooling rate.

Paper Details

Date Published: 18 December 2019
PDF: 8 pages
Proc. SPIE 11208, 25th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 112080Q (18 December 2019); doi: 10.1117/12.2542457
Show Author Affiliations
Vladimir P. Ogibalov, St. Petersburg State Univ. (Russian Federation)


Published in SPIE Proceedings Vol. 11208:
25th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics
Oleg A. Romanovskii; Gennadii G. Matvienko, Editor(s)

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