Small-scale temperature fluctuations associated with gravity waves cause additional radiative cooling of mesopause the region

• Published in: Geophysical research letters Vol. 34; no. 24; pp. L24807 - n/a
• Main Authors: Kutepov, Alexander A., Feofilov, Artem G., Medvedev, Alexander S., Pauldrach, Adalbert W. A., Hartogh, Paul
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.12.2007; Blackwell Publishing Ltd
• Subjects: Acoustic-gravity waves; Atmospheric Composition and Structure; Atmospheric Processes; composition and chemistry; Earth sciences; Earth, ocean, space; Exact sciences and technology; Middle atmosphere; non-LTE; radiative cooling; Radiative processes; radiative cooling; non-LTE; Temperature distribution; Thermosphere; General circulation models; digital simulation; Mesosphere; Perturbation; Variance; corrections; Gravity wave; isotopes; Statistical model; Mesopause; cooling; temperature; Temperature fluctuation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2007GL032392

We present a study of the radiative cooling of the mesosphere and lower thermosphere in the infrared bands of CO2, O3 and H2O due to small‐scale irregular temperature fluctuations caused by gravity waves. These persistent fluctuations are presently not well represented by general circulation models. A statistical model of gravity wave‐induced temperature variations was applied to large‐scale temperature profiles, and the corresponding direct radiative calculations were performed. We show that temperature fluctuations can cause an additional cooling up to 3 K day−1 near the mesopause. The effect is produced mainly by the fundamental 15 μm band of the main CO2 isotope. We found a simple correction depending on the temperature fluctuations variance, which should be added in radiative calculations to the mean temperature profile to account for the additional cooling associated with the unresolved disturbances.