CO&lt;sub&gt;2&lt;/sub&gt;(&lt;i&gt;ν&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt;)-O quenching rate coefficient derived from coincidental SABER/TIMED and Fort Collins lidar observations of the mesosphere and lower thermosphere

Abstract. Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(ν2)-O vibrational levels by collisions with O atoms plays an important role. However, there is a factor of 3–4 discrepancy between various measurements of the CO2-O quenching rate coefficient, kVT. We retrieve kVT in the altitude region 80–110 km from coincident SABER/TIMED and Fort Collins sodium lidar observations by minimizing the difference between measured and simulated broadband limb 15 μm radiances. The retrieved kVT varies from about 5 × 10−12 cm3 s−1 at 87 km to about 7 × 10−12 cm3 s−1 at 104 km. A detailed consideration of retrieval errors and uncertainties indicates deficiency in current understanding the non-LTE formation mechanism of atmospheric 15 μm radiances. An updated mechanism of CO2-O collisional interactions is suggested.

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CO2(ν2)-O quenching rate coefficient derived from coincidental SABER/TIMED and Fort Collins lidar observations of the mesosphere and lower thermosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-9013-2012 ◽

2012 ◽

Vol 12 (19) ◽

pp. 9013-9023 ◽

Cited By ~ 20

Author(s):

A. G. Feofilov ◽

A. A. Kutepov ◽

C.-Y. She ◽

A. K. Smith ◽

W. D. Pesnell ◽

...

Keyword(s):

Rate Coefficient ◽

Lower Thermosphere ◽

Detailed Balance ◽

Quenching Rate ◽

Vibrational Levels ◽

Fort Collins ◽

Atmospheric Observations ◽

Mesosphere And Lower Thermosphere ◽

The Difference ◽

Lidar Observations

Abstract. Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(ν2) vibrational levels by collisions with O atoms plays an important role. However, there is a factor of 3–4 discrepancy between the laboratory measurements of the CO2-O quenching rate coefficient, kVT, and its value estimated from the atmospheric observations. In this study, we retrieve kVT in the altitude region 85–105 km from the coincident SABER/TIMED and Fort Collins sodium lidar observations by minimizing the difference between measured and simulated broadband limb 15 μm radiation. The averaged kVT value obtained in this work is 6.5 ± 1.5 × 10−12 cm3 s−1 that is close to other estimates of this coefficient from the atmospheric observations. However, the retrieved kVT also shows altitude dependence and varies from 5.5 ± 1.1 × 10−12 cm3 s−1 at 90 km to 7.9 ± 1.2 × 10−12 cm3 s−1 at 105 km. Obtained results demonstrate the deficiency in current non-LTE modeling of the atmospheric 15 μm radiation, based on the application of the CO2-O quenching and excitation rates, which are linked by the detailed balance relation. We discuss the possible model improvements, among them accounting for the interaction of the "non-thermal" oxygen atoms with CO2 molecules.

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New Lidar Observations of Ca + in the Mesosphere and Lower Thermosphere Over Arecibo

Geophysical Research Letters ◽

10.1029/2020gl087113 ◽

2020 ◽

Vol 47 (5) ◽

Cited By ~ 1

Author(s):

Shikha Raizada ◽

J. A. Smith ◽

J. Lautenbach ◽

N. Aponte ◽

P. Perillat ◽

...

Keyword(s):

Lower Thermosphere ◽

Mesosphere And Lower Thermosphere ◽

Lidar Observations

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Vibrational populations of near-ultraviolet O2 band systems in the night airglow 1This article is part of a Special issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

Canadian Journal of Physics ◽

10.1139/p2012-010 ◽

2012 ◽

Vol 90 (8) ◽

pp. 741-751

Author(s):

R.L. Gattinger ◽

I.C. McDade ◽

A.L. Broadfoot ◽

W.F.J. Evans ◽

J. Stegman ◽

...

Keyword(s):

Least Squares Method ◽

Band System ◽

Lower Thermosphere ◽

Near Ultraviolet ◽

Vibrational Levels ◽

Mesosphere And Lower Thermosphere ◽

The Individual ◽

Franck Condon ◽

Imaging Spectrograph ◽

Night Airglow

Observations of the limb night airglow spectrum from 250 to 475 nm, emitted from the upper mesosphere and lower thermosphere, are compared with model spectra. Data from the Arizona GLO-1 imaging spectrograph and the OSIRIS spectrograph are combined to form the observed mean airglow spectrum; a tabulated version of this spectrum is included. Model spectra of the individual O2 Herzberg I, II, and III, Chamberlain, and Slanger band systems are combined to simulate the observed mean spectrum. Franck–Condon relative band intensities are used to form a series of basis functions for the upper vibrational levels in each band system. These functions are fitted to the observed airglow spectrum with a least-squares method, the relative vibrational populations are derived and discussed.

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Simultaneous, common-volume lidar observations and theoretical studies of correlations among Fe/Na layers and temperatures in the mesosphere and lower thermosphere at Boulder Table Mountain (40°N, 105°W), Colorado

Journal of Geophysical Research Atmospheres ◽

10.1002/jgrd.50670 ◽

2013 ◽

Vol 118 (15) ◽

pp. 8748-8759 ◽

Cited By ~ 8

Author(s):

Wentao Huang ◽

Xinzhao Chu ◽

Chester S. Gardner ◽

Zhangjun Wang ◽

Weichun Fong ◽

...

Keyword(s):

Lower Thermosphere ◽

Theoretical Studies ◽

Table Mountain ◽

Mesosphere And Lower Thermosphere ◽

Lidar Observations

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Connection between the length of day and wind measurements in the mesosphere and lower thermosphere at mid and high latitudes

10.5194/angeo-2018-51 ◽

2018 ◽

Author(s):

Sven Wilhelm ◽

Gunter Stober ◽

Vivien Matthias ◽

Christoph Jacobi ◽

Damian J. Murphy

Keyword(s):

Large Scale ◽

Lower Thermosphere ◽

Momentum Conservation ◽

Density Variation ◽

Day Length ◽

The Sun ◽

The Earth ◽

Geophysical Processes ◽

Mesosphere And Lower Thermosphere ◽

The Difference

Abstract. This work presents a connection between the density variation within the mesosphere and lower thermosphere (MLT) and changes in the intensity of the solar radiation. On a seasonal time scale, these changes take place due to the revolution of the Earth around the Sun. While the Earth, during the northern hemispheric winter, is closer to the Sun, the upper mesosphere expands due to an increased radiation intensity, which results in changes in density at these heights. Theses density variations, i.e. a vertical redistribution of atmospheric mass, have an effect on the rotation rate of Earth's upper atmosphere owing to angular momentum conservation. In order to test this effect we applied a theoretical model, which shows a decrease of the atmospheric rotation speed of about ~ 4 m/s in the case of a density change of 1 % between 70 and 100 km. To support this statement, we compare the wind variability obtained from meteor radar (MR) and MLS satellite observations with fluctuations in the length of a day (LOD). The LOD is defined as the difference between the astronomical determined time the Earth needs for a full turnaround and a standard day length of 86.400 seconds. Changes in the LOD on time scales of a year and less are primarily driven by tropospheric large scale geophysical processes. A global increase of eastward directed winds leads, due to friction with the Earth's surface, to an acceleration of the Earth's rotation by up to a few milliseconds per rotation. The LOD shows an increase during northern winter and decrease during summer, which corresponds to changes in the MLT density due to the Earth – Sun movement. Further, we show that, even after removing the seasonal and solar cycle variations, the wind and the LOD are connected, by analyzing trends for the years 2005–2016.

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Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

Journal of the Atmospheric Sciences ◽

10.1175/jas3612.1 ◽

2005 ◽

Vol 62 (12) ◽

pp. 4384-4399 ◽

Cited By ~ 104

Author(s):

Rolando R. Garcia ◽

Ruth Lieberman ◽

James M. Russell ◽

Martin G. Mlynczak

Keyword(s):

Large Scale ◽

Middle Atmosphere ◽

Lower Thermosphere ◽

Normal Modes ◽

Zonal Winds ◽

Broadband Emission ◽

Summer Hemisphere ◽

Mean Structure ◽

Mesosphere And Lower Thermosphere ◽

The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

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