scholarly journals Radiative and energetic constraints on the global annual mean atomic oxygen concentration in the mesopause region

2013 ◽  
Vol 118 (11) ◽  
pp. 5796-5802 ◽  
Author(s):  
Martin G. Mlynczak ◽  
Linda H. Hunt ◽  
Christopher J. Mertens ◽  
B. Thomas Marshall ◽  
James M. Russell ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Atomic Oxygen ◽  
Mesopause Region ◽  
Energetic Constraints ◽  
Atomic Oxygen Concentration

scholarly journals Radiative constraints on the minimum atomic oxygen concentration in the mesopause region

2013 ◽  
Vol 40 (14) ◽  
pp. 3777-3780 ◽  
Author(s):  
Martin G. Mlynczak ◽  
Linda A. Hunt ◽  
B. Thomas Marshall ◽  
Christopher J. Mertens ◽  
James M. Russell ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Atomic Oxygen ◽  
Mesopause Region ◽  
Atomic Oxygen Concentration

scholarly journals The role of atomic oxygen concentration in the ionization balance of the lower ionosphere during solar proton events

2008 ◽  
Vol 26 (1) ◽  
pp. 131-143 ◽  
Author(s):  
A. Osepian ◽  
V. Tereschenko ◽  
P. Dalin ◽  
S. Kirkwood
Keyword(s):  
Electron Density ◽  
Oxygen Concentration ◽  
Atomic Oxygen ◽  
Negative Ions ◽  
Solar Proton ◽  
Negative Ion ◽  
Proton Event ◽  
Density Profiles ◽  
Oxygen Profile ◽  
Atomic Oxygen Concentration

Abstract. The influence of atomic oxygen concentration on the height distribution of the main positive and negative ions and on electron density in the mesosphere is studied for the conditions prevailing during the solar proton event on 17 January 2005. It is shown by numerical modeling that the electron and ion density profiles are strongly dependent on the choice of the atomic oxygen profile. Experimental measurements of the electron density are used as the criterion for choosing the atomic oxygen profile in the mesosphere. With the help of modeling, the atomic oxygen profile in the daytime in the winter mesosphere is found to lead to a model electron density profile best matching the electron density profile obtained experimentally. As a result, with the help of modeling, we find the atomic oxygen profiles at various solar zenith angles in the winter mesosphere which lead to model electron density profiles matching the electron density profiles obtained experimentally. Alteration of the atomic oxygen concentration leads to a redistribution of the abundance of both positive and negative ion constituents, with changes in their total concentrations and transition heights. In consequence this results in changes of the electron density and effective recombination coefficient. For conditions of low concentration of atomic oxygen (during a solar proton event), the formation of cluster ions is the key process determining electron and ion densities at altitudes up to 77 km. The complex negative CO3− ion is formed up to about 74 km and the final NO3− ion, which is stable in relation to the atomic oxygen, is the dominant negative ion up to 74 km. As a result the transition heights between cluster ions and molecular ions and between negative ions and electron density are located at 77 km and 66 km, respectively.

scholarly journals Atomic oxygen retrievals in the MLT region from SCIAMACHY nightglow limb measurements

2014 ◽  
Vol 7 (10) ◽  
pp. 10829-10881
Author(s):  
O. Lednyts'kyy ◽  
C. von Savigny ◽  
K.-U. Eichmann ◽  
M. G. Mlynczak
Keyword(s):  
Time Series ◽  
Oxygen Concentration ◽  
Atomic Oxygen ◽  
Emission Rate ◽  
Band Pass Filter ◽  
Density Profiles ◽  
Solar Cycle Variation ◽  
The Impact ◽  
Atomic Oxygen Concentration ◽  
Mlt Region

Abstract. Vertical profiles of atomic oxygen concentration in the mesosphere and lower thermosphere (MLT) region were retrieved from sun-synchronous SCIAMACHY/Envisat limb observations of the oxygen 557.7 nm green line emission occurring in the terrestrial nightglow. A band pass filter with noise detection was applied to eliminate contributions from other emissions, the impact of noise and auroral activity. Assuming horizontal homogeneity of each atmospheric layer, and absence of absorption and scattering, vertical volume emission rate profiles were retrieved from integrated limb emission rate profiles. The radiative transfer problem was treated with a linear forward model and inverted using regularized total least squares minimization. Atomic oxygen concentration ([O]) profiles were retrieved at altitudes from 85 to 105 km with approximately 4 km vertical resolution for the period from August 2002 to April 2012 at a constant local time (LT) of approximately 22:00. The retrieval of [O] profiles was based on the generally accepted 2-step Barth transfer scheme including consideration of quenching processes and the use of different available sources of temperature and atmospheric density profiles. A sensitivity analysis was performed for the retrieved [O] profiles to estimate the maximum uncertainty, assuming independent contributions of uncertainty components. The retrieved [O] profiles were compared with reference [O] profiles measured by SABER/TIMED and modelled using NRLMSISE-00 and SD-WACCM4. A comparison of the retrieved [O] profiles with the reference [O] profiles enabled the selection of the most appropriate photochemical model accounting for quenching processes and the most appropriate source of temperature and density profiles for further application of our approach to the [O] profile retrieval. The obtained [O] profile time series show characteristic seasonal variations in agreement with atmospheric models and satellite observations based on analysis of OH Meinel band emissions. Furthermore, a pronounced 11 year solar cycle variation can be identified in the atomic oxygen concentration time series, which will be the subject of further studies.

scholarly journals Synchronous <I>Nm</I>F2 and <I>Nm</I>E daytime variations as a key to the mechanism of quiet-time F2-layer disturbances

2007 ◽  
Vol 25 (2) ◽  
pp. 483-493 ◽  
Author(s):  
A. V. Mikhailov ◽  
V. H. Depuev ◽  
A. H. Depueva
Keyword(s):  
Oxygen Concentration ◽  
Atomic Oxygen ◽  
Basic Mechanism ◽  
Morphological Features ◽  
Quiet Time ◽  
Thermospheric Wind ◽  
Neutral Gas ◽  
Atomic Oxygen Concentration

Abstract. The observed NmF2 and NmE variations were analyzed for the periods of positive and negative quiet-time F2-layer disturbances (Q-disturbances) observed in the midlatitude daytime F2-layer to specify the mechanism of their origin. The noontime δNmF2 and δNmE deviations demonstrate a synchronous type of variation which can be explained by vertical gas motion in the thermosphere. This neutral gas motion should result in atomic abundance variations, the latter being confirmed by the Millstone Hill ISR observations for periods of positive and negative Q-disturbance events. The analysis of the ISR data has shown that atomic oxygen concentration variations are the main cause of the daytime F2-layer Q-disturbances. The auroral heating which controls the poleward thermospheric wind is considered to be the basic mechanism for the Q-disturbances, however, the specific mechanisms of positive and negative Q-disturbances are different. Some morphological features of the Q-disturbances revealed earlier are explained in the scope of the proposed concept.

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