scholarly journals Retrieval of molecular nitrogen and molecular oxygen densities in the upper mesosphere and lower thermosphere using ground-based lidar measurements

2001 ◽  
Vol 106 (D10) ◽  
pp. 10313-10323 ◽  
Author(s):  
M. M. Mwangi ◽  
R. J. Sica ◽  
P. S. Argall
Keyword(s):  
Molecular Oxygen ◽  
Molecular Nitrogen ◽  
Lower Thermosphere ◽  
Lidar Measurements ◽  
Mesosphere And Lower Thermosphere ◽  
Ground Based Lidar

Model of Daytime Oxygen Emissions in the Mesopause Region and Above: New Results

2021 ◽  
Author(s):  
Valentine Yankovsky ◽  
Ekaterina Vorobeva ◽  
Rada Manuilova ◽  
Irina Mironova
Keyword(s):  
Molecular Oxygen ◽  
Excited States ◽  
Lower Thermosphere ◽  
Basic Research ◽  
Vibrationally Excited ◽  
Mesopause Region ◽  
Mesosphere And Lower Thermosphere ◽  
Basic Research Grant ◽  
The 19Th Century ◽  
Excited Oxygen

<p>Atmospheric emissions of atomic and molecular oxygen have been observed since the middle of the 19th century. In the last decades, it has been shown that emissions of excited oxygen atom O(<sup>1</sup>D) and molecular oxygen in electronically-vibrationally excited states O<sub>2</sub>(b<sup>1</sup>Σ<sup>+</sup><sub>g</sub>, v) and O<sub>2</sub>(a<sup>1</sup>Δ<sub>g</sub>, v) are related by a unified photochemical mechanism in the mesosphere and lower thermosphere (MLT). The current study is performed in the framework of the state-of-the-art model of ozone and molecular oxygen photodissociation in the daytime MLT. In particular, the study includes a detailed description of the formation mechanism for excited oxygen components in the daytime MLT and presents the comparison of widely used photochemical models. The study also demonstrates new results such as i) new suggestions about possible products of collisional reactions of electronically-vibrationally excited oxygen molecules with atomic oxygen and ii) new estimates of O<sub>2</sub>(b<sup>1</sup>Σ<sup>+</sup><sub>g</sub>, v = 0 – 10) radiative lifetimes which are necessary for solving inverse problems in the lower thermosphere. Moreover, special attention is given to the Barth’s mechanism in order to demonstrate that its contribution to O<sub>2</sub>(b<sup>1</sup>Σ<sup>+</sup><sub>g</sub>, v) and O<sub>2</sub>(a<sup>1</sup>Δ<sub>g</sub>, v) populations is neglectable in daytime conditions regardless of fitting coefficients. In addition, possible applications of the daytime oxygen emissions are presented, e.g., the altitude profiles O(<sup>3</sup>P), O<sub>3</sub> and CO<sub>2</sub> can be retrieved by solving inverse photochemical problems where emissions from electronically vibrationally excited states of O<sub>2</sub> are used as proxies. The funding of V.Y., R.M. and I.M. was partly provided by the Russian Fund for Basic Research (grant RFBR No. 20-05-00450).</p>

scholarly journals A comparison of Rayleigh and sodium lidar temperature climatologies

2007 ◽  
Vol 25 (1) ◽  
pp. 27-35 ◽  
Author(s):  
P. S. Argall ◽  
R. J. Sica
Keyword(s):  
United States ◽  
Unique Feature ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Western United States ◽  
Lidar Measurements ◽  
Climatological Model ◽  
Significant Disagreement ◽  
Mesosphere And Lower Thermosphere ◽  
Rayleigh Lidar

Abstract. Temperature measurements from the PCL Rayleigh lidar located near London, Canada, taken during the 11 year period from 1994 to 2004 are used to form a temperature climatology of the middle atmosphere. A unique feature of the PCL temperature climatology is that it extends from 35 to 95 km allowing comparison with other Rayleigh lidar climatologies (which typically extend up to about 85 km), as well as with climatologies derived from sodium lidar measurements which extend from 83 to 108 km. The derived temperature climatology is compared to the CIRA-86 climatological model and to other lidar climatologies, both Rayleigh and sodium. The PCL climatology agrees well with the climatologies of other Rayleigh lidars from similar latitudes, and like these other climatologies shows significant differences from the CIRA-86 temperatures in the mesosphere and lower thermosphere. Significant disagreement is also found between the PCL climatology and sodium lidar climatologies measured in the central and western United States at similar latitudes, with the PCL climatology consistently 10 to 15 K cooler in the 85 to 90 km region.

scholarly journals Overturning instability in the mesosphere and lower thermosphere: analysis of instability conditions in lidar data

2009 ◽  
Vol 27 (7) ◽  
pp. 2937-2945 ◽  
Author(s):  
L. Hurd ◽  
M. F. Larsen ◽  
A. Z. Liu
Keyword(s):  
New Mexico ◽  
Inflection Point ◽  
Lower Thermosphere ◽  
Static Stability ◽  
Lidar Data ◽  
University Of Illinois ◽  
Lidar Measurements ◽  
Mesosphere And Lower Thermosphere ◽  
The University ◽  
Vertical Scales

Abstract. Resonant sodium lidar measurements from the transition region between the mesosphere and lower thermosphere have revealed frequently-occurring overturning events characterized by vertical scales of ~3–6 km and timescales of several hours. Larsen et al. (2004) proposed that a convective roll instability, similar to that found in the planetary boundary layer, is the likely mechanism responsible for the events. This type of instability requires an inflection point in the background winds near the center of the vortex roll with a low static stability region capped by an inversion. The earlier paper argued that the conditions required to support the instability are common in the altitude range where the features are found. In this paper, we use data from the University of Illinois sodium lidar that was located at the Starfire Optical Range near Albuquerque, New Mexico, and from the Maui/MALT Lidar Facility in Hawaii and present several cases that are used to examine the behavior of the inflection point in detail as a function of time during the evolution of the overturning event. In addition, we examine the background static stability conditions using the temperature data from the lidar.

scholarly journals Model of Daytime Oxygen Emissions in the Mesopause Region and Above: A Review and New Results

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 116 ◽  
Author(s):  
Valentine Yankovsky ◽  
Ekaterina Vorobeva
Keyword(s):  
Oxygen Atom ◽  
Molecular Oxygen ◽  
Excited States ◽  
Atomic Oxygen ◽  
Lower Thermosphere ◽  
Atmospheric Emissions ◽  
Vibrationally Excited ◽  
Mesopause Region ◽  
Mesosphere And Lower Thermosphere ◽  
Excited Oxygen

Atmospheric emissions of atomic and molecular oxygen have been observed since the middle of 19th century. In the last decades, it has been shown that emissions of excited oxygen atom O(1D) and molecular oxygen in electronically–vibrationally excited states O2(b1Σ+g, v) and O2(a1Δg, v) are related by a unified photochemical mechanism in the mesosphere and lower thermosphere (MLT). The current paper consists of two parts: a review of studies related to the development of the model of ozone and molecular oxygen photodissociation in the daytime MLT and new results. In particular, the paper includes a detailed description of formation mechanism for excited oxygen components in the daytime MLT and presents comparison of widely used photochemical models. The paper also demonstrates new results such as new suggestions about possible products for collisional reactions of electronically–vibrationally excited oxygen molecules with atomic oxygen and new estimations of O2(b1Σ+g, v = 0–10) radiative lifetimes which are necessary for solving inverse problems in the lower thermosphere. Moreover, special attention is given to the “Barth’s mechanism” in order to demonstrate that for different sets of fitting coefficients its contribution to O2(b1Σ+g, v) and O2(a1Δg, v) population is neglectable in daytime conditions. In addition to the review and new results, possible applications of the daytime oxygen emissions are presented, e.g., the altitude profiles O(3P), O3 and CO2 can be retrieved by solving inverse photochemical problems when emissions from electronically vibrationally excited states of O2 molecule are used as proxies.

scholarly journals Electronic kinetics of molecular nitrogen and molecular oxygen in high-latitude lower thermosphere and mesosphere

2010 ◽  
Vol 28 (1) ◽  
pp. 181-192 ◽  
Author(s):  
A. S. Kirillov
Keyword(s):  
Molecular Oxygen ◽  
High Latitude ◽  
Molecular Nitrogen ◽  
Lower Thermosphere ◽  
Rate Coefficients ◽  
Triplet States ◽  
Quenching Rate ◽  
Principal Mechanism ◽  
Auroral Electron ◽  
Electronically Excited

Abstract. Total quenching rate coefficients of Herzberg states of molecular oxygen and three triplet states of molecular nitrogen in the collisions with O2 and N2 molecules are calculated on the basis of quantum-chemical approximations. The calculated rate coefficients of electronic quenching of O2* and N2* molecules show a good agreement with available experimental data. An influence of collisional processes on vibrational populations of electronically excited N2 and O2 molecules is studied for the altitudes of high-latitude lower thermosphere and mesosphere during auroral electron precipitation. It is indicated that molecular collisions of metastable nitrogen N2(A3Σu*) with O2 molecules are principal mechanism in electronic excitation of both Herzberg states c1Σu&minus, A'3Δu, A3Σu+ and high vibrational levels of singlet states a1Δg and b1Σg+ of molecular oxygen O2 at these altitudes.

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

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
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.

Climatological modeling of horizontal winds in the mesosphere and lower thermosphere over a mid-latitude station in China

2015 ◽  
Vol 56 (7) ◽  
pp. 1354-1365 ◽  
Author(s):  
Xin Yao ◽  
Tao Yu ◽  
Biqiang Zhao ◽  
You Yu ◽  
Libo Liu ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Latitude Station ◽  
Mesosphere And Lower Thermosphere
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