Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing

Feofilov, Artem; Kutepov, A. A.

doi:10.1007/s10712-012-9204-0

Cited by 50 publications

(35 citation statements)

References 117 publications

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“…The global low temperature at 95-100 km is due to the radiative balance there. As elsewhere in the middle atmosphere, CO 2 radiative transfer cools the MLT (Fomichev 2009;Feofilov and Kutepov 2012). The primary energy for heating in the MLT is absorption of solar energy by O 2 .…”

Section: Zonal Mean Temperature and Windsmentioning

confidence: 99%

“…In practice, it is difficult to determine the diabatic heating because the concentrations of radiatively active gases are not well known due to high variability, including rapid diurnal changes, and also because radiative transfer is complex in the MLT because the CO 2 emissions responsible for most of the cooling are not in local thermodynamic equilibrium (LTE; see Feofilov and Kutepov 2012). Lieberman et al (2000) derived the diabatic circulation using temperature measurements from HRDI.…”

Section: Mean Meridional Circulationmentioning

confidence: 99%

“…Companion papers by Feofilov and Kutepov (2012) and Sinnhuber (2012) discuss the MLT radiative balance and the response of MLT chemistry to energetic particles, respectively. Although this paper gives many references for observational and theoretical studies, the reference list is not comprehensive.…”

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confidence: 99%

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Global Dynamics of the MLT

2012

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The transition between the middle atmosphere and the thermosphere is known as the MLT region (for mesosphere and lower thermosphere). This area has some characteristics that set it apart from other regions of the atmosphere. Most notably, it is the altitude region with the lowest overall temperature and has the unique characteristic that the temperature is much lower in summer than in winter. The summer-to-winter-temperature gradient is the result of adiabatic cooling and warming associated with a vigorous circulation driven primarily by gravity waves. Tides and planetary waves also contribute to the circulation and to the large dynamical variability in the MLT. The past decade has seen much progress in describing and understanding the dynamics of the MLT and the interactions of dynamics with chemistry and radiation. This review describes recent observations and numerical modeling as they relate to understanding the dynamical processes that control the MLT and its variability. Results from the Whole Atmosphere Community Climate Model (WACCM), which is a comprehensive high-top general circulation model with interactive chemistry, are used to illustrate the dynamical processes. Selected observations from the Sounding the Atmosphere with Broadband Emission Radiometry (SABER) instrument are shown for comparison. WACCM simulations of MLT dynamics have some differences with observations. These differences and other questions and discrepancies described in recent papers point to a number of ongoing uncertainties about the MLT dynamical system.

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Section: Zonal Mean Temperature and Windsmentioning

confidence: 99%

Section: Mean Meridional Circulationmentioning

confidence: 99%

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Global Dynamics of the MLT

2012

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“…A non-LTE (non-local thermodynamical equilibrium) analysis was applied to CO 2 and OH using the non-LTE ALI-ARMS (Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) code package Gusev and Kutepov, 2003;Feofilov and Kutepov, 2012), which is based on the accelerated lambda iteration approach (Rybicki and Hummer, 1991).…”

Section: Non-lte Modelmentioning

confidence: 99%

“…Our CO 2 non-LTE model is described in detail by Feofilov and Kutepov (2012). We modified its nighttime version to account for the "direct" mechanism, Reactions (R1)-(R3), in a way consistent with that of López-Puertas et al (2004) and added the "indirect" mechanism of Sharma et al (2015) and Kalogerakis et al (2016) as described in detail below.…”

Section: Non-lte Modelmentioning

confidence: 99%

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO2(ν3) and OH(ν) emission models

et al. 2017

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Abstract. In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν) in the nighttime mesosphere to the CO 2 (ν 3 ) vibration, OH(ν) ⇒ N 2 (ν) ⇒ CO 2 (ν 3 ), was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8-3 N 2 (1) molecules instead of one N 2 (1) molecule in each quenching reaction of OH(ν) + N 2 (0). Recently a new "indirect" channel of the OH(ν) energy transfer to N 2 (ν) vibrations, OH(ν) ⇒ O( 1 D) ⇒ N 2 (ν), was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9) + O( 3 P) was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO 2 (ν 3 ) and OH(ν) vibrational level populations and emissions. We also compared our calculations with (a) the SABER/TIMED nighttime 4.3 µm CO 2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere-lower thermosphere (MLT) and (b) with ground-and space-based observations of OH(ν) densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO 2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν) density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν) energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new "indirect" mechanism efficiently removes at least five quanta in each OH(ν ≥ 5) + O( 3 P) collision and provides the OH(ν) distributions which agree with both SABER limb OH emission observations and ground-and space-based OH(ν) density measurements. This analysis suggests that the important mechanism of the OH(ν) vibrational energy relaxation in the nighttime MLT, which was missing in the emission models of this atmospheric layer, has been finally identified.

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Cooling of the Martian thermosphere by CO₂radiation and gravity waves: An intercomparison study with two general circulation models

Medvedev

González‐Galindo

Yiğit

et al. 2015

J. Geophys. Res. Planets

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Observations show that the lower thermosphere of Mars (∼100–140 km) is up to 40 K colder than the current general circulation models (GCMs) can reproduce. Possible candidates for physical processes missing in the models are larger abundances of atomic oxygen facilitating stronger CO2 radiative cooling and thermal effects of gravity waves. Using two state‐of‐the‐art Martian GCMs, the Laboratoire de Météorologie Dynamique and Max Planck Institute models that self‐consistently cover the atmosphere from the surface to the thermosphere, these physical mechanisms are investigated. Simulations demonstrate that the CO2 radiative cooling with a sufficiently large atomic oxygen abundance and the gravity wave‐induced cooling can alone result in up to 40 K colder temperature in the lower thermosphere. Accounting for both mechanisms produce stronger cooling at high latitudes. However, radiative cooling effects peak above the mesopause, while gravity wave cooling rates continuously increase with height. Although both mechanisms act simultaneously, these peculiarities could help to further quantify their relative contributions from future observations.

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Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing

Cited by 50 publications

References 117 publications

Global Dynamics of the MLT

Global Dynamics of the MLT

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO<sub>2</sub>(<i>ν</i><sub>3</sub>) and OH(<i>ν</i>) emission models

Cooling of the Martian thermosphere by CO₂radiation and gravity waves: An intercomparison study with two general circulation models

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Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing

Cited by 50 publications

References 117 publications

Global Dynamics of the MLT

Global Dynamics of the MLT

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO&lt;sub&gt;2&lt;/sub&gt;(&lt;i&gt;ν&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;) and OH(&lt;i&gt;ν&lt;/i&gt;) emission models

Cooling of the Martian thermosphere by CO2radiation and gravity waves: An intercomparison study with two general circulation models

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Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO<sub>2</sub>(<i>ν</i><sub>3</sub>) and OH(<i>ν</i>) emission models

Cooling of the Martian thermosphere by CO₂radiation and gravity waves: An intercomparison study with two general circulation models