scholarly journals The effect of vibrationally excited nitrogen on the low-latitude ionosphere

1997 ◽  
Vol 15 (11) ◽  
pp. 1422-1428 ◽  
Author(s):  
B. Jenkins ◽  
G. J. Bailey ◽  
A. E. Ennis ◽  
R. J. Moffett
Keyword(s):  
Excited States ◽  
Atomic Oxygen ◽  
Molecular Nitrogen ◽  
Low Latitude ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
Oxygen Ions ◽  
Ionosphere Model ◽  
Low Latitude Ionosphere ◽  
Excited Nitrogen

Abstract. The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.

Reaction of atomic oxygen ions with vibrationally excited nitrogen molecules

1967 ◽  
Vol 15 (3) ◽  
pp. 401-406 ◽  
Author(s):  
A.L. Schmeltekopf ◽  
F.C. Fehsenfeld ◽  
G.I. Oilman ◽  
E.E. Ferguson
Keyword(s):  
Atomic Oxygen ◽  
Vibrationally Excited ◽  
Oxygen Ions ◽  
Excited Nitrogen

scholarly journals Global modelling study (GSM TIP) of the ionospheric effects of excited <i>N<sub>2</sub></i>, convection and heat fluxes by comparison with EISCAT and satellite data for 31 July 1990

1996 ◽  
Vol 14 (12) ◽  
pp. 1362-1374 ◽  
Author(s):  
Yu. N. Korenkov ◽  
V. V. Klimenko ◽  
M. Förster ◽  
V. A. Surotkin ◽  
J. Smilauer
Keyword(s):  
Satellite Data ◽  
Molecular Nitrogen ◽  
Reaction Rates ◽  
Heat Fluxes ◽  
High Solar Activity ◽  
Plasma Parameters ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
Excited Nitrogen ◽  
Good Agreement

Abstract. Near-earth plasma parameters were calculated using a global numerical self-consistent and time-dependent model of the thermosphere, ionosphere and protonosphere (GSM TIP). The model results are compared with experimental data of different origin, mainly EISCAT measurements and simultaneous satellite data (Ne and ion composition). Model runs with varying inputs of auroral FAC distributions, temperature of vibrationally excited nitrogen and photoelectron energy escape fluxes are used to make adjustments to the observations. The satellite data are obtained onboard Active and its subsatellite Magion-2 when they passed nearby the EISCAT station around 0325 and 1540 UT on 31 July 1990 at a height of about 2000 and 2200 km, respectively. A strong geomagnetic disturbance was observed two days before the period under study. Numerical calculations were performed with consideration of vibrationally excited nitrogen molecules for high solar-activity conditions. The results show good agreement between the incoherent-scatter radar measurements (Ne, Te, Ti) and model calculations, taking into account the excited molecular nitrogen reaction rates. The comparison of model results of the thermospheric neutral wind shows finally a good agreement with the HWM93 empirical wind model.

scholarly journals The role of vibrationally excited oxygen and nitrogen in the ionosphere during the undisturbed and geomagnetic storm period of 6-12 April 1990

1998 ◽  
Vol 16 (5) ◽  
pp. 589-601 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Loss Rate ◽  
Boltzmann Distribution ◽  
Rate Coefficients ◽  
Ion Chemistry ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
F Region ◽  
Neutral Temperature ◽  
The Difference ◽  
Excited Nitrogen

Abstract. We present a comparison of the observed behavior of the F-region ionosphere over Millstone Hill during the geomagnetically quiet and storm periods of 6–12 April 1990 with numerical model calculations from the IZMIRAN time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The major enhancement to the IZMIRAN model developed in this study is the use of a new loss rate of O+(4S) ions as a result of new high-temperature flowing afterglow measurements of the rate coefficients K1 and K2 for the reactions of O+(4S) with N2 and O2. The deviations from the Boltzmann distribution for the first five vibrational levels of O2(v) were calculated, and the present study suggests that these deviations are not significant. It was found that the difference between the non-Boltzmann and Boltzmann distribution assumptions of O2(v) and the difference between ion and neutral temperature can lead to an increase of up to about 3 or a decrease of up to about 4 of the calculated NmF2 as a result of a respective increase or a decrease in K2. The IZMIRAN model reproduces major features of the data. We found that the inclusion of vibrationally excited N2(v > 0) and O2(v > 0) in the calculations improves the agreement between the calculated NmF2 and the data on 6, 9, and 10 April. However, both the daytime and nighttime densities are reproduced by the IZMIRAN model without the vibrationally excited nitrogen and oxygen on 8 and 11 April better than the IZMIRAN model with N2(v > 0) and O2(v > 0). This could be due to possible uncertainties in model neutral temperature and densities, EUV fluxes, rate coefficients, and the flow of ionization between the ionosphere and plasmasphere, and possible horizontal divergence of the flux of ionization above the station. Our calculations show that the increase in the O+ + N2 rate factor due to N2(v > 0) produces a 5-36 decrease in the calculated daytime peak density. The increase in the O++ O2 loss rate due to vibrational-ly excited O2 produces 8-46 reductions in NmF2. The effects of vibrationally excited O2 and N2 on Ne and Te are most pronounced during the daytime.Key words. Ion chemistry and composition · Ionosphere – atmosphere interactions · Ionospheric disturbances

scholarly journals Modification of conductivity due to acceleration of the ionospheric medium

2008 ◽  
Vol 26 (8) ◽  
pp. 2111-2130 ◽  
Author(s):  
V. V. Denisenko ◽  
H. K. Biernat ◽  
A. V. Mezentsev ◽  
V. A. Shaidurov ◽  
S. S. Zamay
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Electric Current ◽  
Magnetic Field Line ◽  
Conducting Layer ◽  
Low Latitude ◽  
Ionosphere Model ◽  
Zero Current ◽  
Night Side ◽  
Low Latitude Ionosphere

Abstract. A quantitative division of the ionosphere into dynamo and motor regions is performed on the base of empirical models of space distributions of ionospheric parameters. Pedersen and Hall conductivities are modified to represent an impact of acceleration of the medium because of Ampére's force. It is shown that the currents in the F2 layer are greatly reduced for processes of a few hours duration. This reduction is in particular important for the night-side low-latitude ionosphere. The International Reference Ionosphere model is used to analyze the effect quantitatively. This model gives a second high conducting layer in the night-side low-latitude ionosphere that reduces the electric field and equatorial electrojets, but intensifies night-side currents during the short-term events. These currents occupy regions which are much wider than those of equatorial electrojets. It is demonstrated that the parameter σd=σP+σHΣH/ΣP that involves the integral Pedersen and Hall conductances ΣP, ΣH ought to be used instead of the local Cowling conductivity σC in calculations of the electric current density in the equatorial ionosphere. We may note that Gurevich et al. (1976) derived a parameter similar to σd for more general conditions as those which we discuss in this paper; a more detailed description of this point is given in Sect. 6. Both, σd and σC, appear when a magnetic field line is near a nonconducting domain which means zero current through the boundary of this domain. The main difference between σd and σC is that σd definition includes the possibility for the electric current to flow along a magnetic field line in order to close all currents which go to this line from neighboring ones. The local Cowling conductivity σC corresponds to the current closure at each point of a magnetic field line. It is adequate only for a magnetic field line with constant local conductivity at the whole line when field-aligned currents do not exist because of symmetry, but σC=σd in this case. So, there is no reason to use the local Cowling conductivity while the Cowling conductance ΣC=ΣP+ΣH2/ΣP is a useful and well defined parameter.

scholarly journals Observations and model calculations of an additional layer in the topside ionosphere above Fortaleza, Brazil

1997 ◽  
Vol 15 (6) ◽  
pp. 753-759 ◽  
Author(s):  
B. Jenkins ◽  
G. J. Bailey ◽  
M. A. Abdu ◽  
I. S. Batista ◽  
N. Balan
Keyword(s):  
Vertical Component ◽  
Topside Ionosphere ◽  
Neutral Wind ◽  
Geomagnetic Equator ◽  
Low Latitude ◽  
Model Calculations ◽  
Additional Layer ◽  
Ionosphere Model

Abstract. Calculations using the Sheffield University plasmasphere ionosphere model have shown that under certain conditions an additional layer can form in the low latitude topside ionosphere. This layer (the F3 layer) has subsequently been observed in ionograms recorded at Fortaleza in Brazil. It has not been observed in ionograms recorded at the neighbouring station São Luis. Model calculations have shown that the F3 layer is most likely to form in summer at Fortaleza due to a combination of the neutral wind and the E×B drift acting to raise the plasma. At the location of São Luis, almost on the geomagnetic equator, the neutral wind has a smaller vertical component so the F3 layer does not form.

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 Low latitude ionosphere-thermosphere dynamics studies with inosonde chain in Southeast Asia

2007 ◽  
Vol 25 (7) ◽  
pp. 1569-1577 ◽  
Author(s):  
T. Maruyama ◽  
M. Kawamura ◽  
S. Saito ◽  
K. Nozaki ◽  
H. Kato ◽  
...  
Keyword(s):  
Magnetic Equator ◽  
Conjugate Points ◽  
Wind Model ◽  
Low Latitude ◽  
Model Calculations ◽  
Neutral Winds ◽  
West Sumatra ◽  
Ionospheric Height ◽  
Low Latitude Ionosphere ◽  
Magnetic Meridian

Abstract. An ionosonde network consisting of a meridional chain and an equatorial pair was established in the Southeast Asian area. Three of four ionosondes are along the magnetic meridian of 100° E; two are close to the magnetic conjugate points in Northern Thailand and West Sumatra, Indonesia, and the other is near the magnetic equator in the Malay Peninsula, Thailand. The fourth ionosonde is also near the magnetic equator in Vietnam but separated by about 6.3° towards east from the meridional chain. For a preliminary data analysis, nighttime ionospheric height variations at the three stations of the meridional chain were examined. The results demonstrate that the coordination of the network has a great potential for studying ionosphere/thermosphere dynamics. Through the assistance of model calculations, thermospheric neutral winds were inferred and compared with the HWM93 empirical thermospheric wind model. Higher-order wind variations that are not represented in the empirical model were found.

scholarly journals The role of vibrationally excited nitrogen and oxygen in the ionosphere over Millstone Hill during 16-23 March, 1990

2000 ◽  
Vol 18 (8) ◽  
pp. 957-966
Author(s):  
A. V. Pavlov ◽  
K.-I. Oyama
Keyword(s):  
Electron Density ◽  
Boltzmann Distribution ◽  
Ion Chemistry ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
Maximum Value ◽  
Vibrational Levels ◽  
Electron Density And Temperature ◽  
Excited Nitrogen ◽  
Distribution Assumption

Abstract. We present a comparison of the observed behavior of the F region ionosphere over Millstone Hill during the geomagnetically quiet and storm period on 16-23 March, 1990, with numerical model calculations from the time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The effects of vibrationally excited N2(v) and O2(v) on the electron density and temperature are studied using the N2(v) and O2(v) Boltzmann and non-Boltzmann distribution assumptions. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at vibrational levels v = 1 and 2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The N2(v) and O2(v) non-Boltzmann distribution assumption leads to the decrease of the calculated daytime NmF2 up to a factor of 1.44 (maximum value) in comparison with the N2(v) and O2(v) Boltzmann distribution assumption. The resulting effects of N2(v > 0) and O2(v > 0) on the NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2.8 (maximum value) for Boltzmann populations of N2(v) and O2(v) and up to a factor of 3.5 (maximum value) for non-Boltzmann populations of N2(v) and O2(v) . This decrease in electron density results in the increase of the calculated daytime electron temperature up to about 1040-1410 K (maximum value) at the F2 peak altitude giving closer agreement between the measured and modeled electron temperatures. Both the daytime and nighttime densities are not reproduced by the model without N2(v > 0) and O2(v > 0) , and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement. The effects of vibrationally excited O2 and N2 on the electron density and temperature are most pronounced during daytime.Key words: Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions; ionospheric disturbances)

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