Electron temperature and electron density in the F-region of the ionosphere. II. The role of atomic oxygen and molecular nitrogen

1987 ◽  
Vol 49 (9) ◽  
pp. 873-887 ◽  
Author(s):  
P.J.S Williams ◽  
J.N McDonald
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Atomic Oxygen ◽  
Molecular Nitrogen ◽  
F Region

THE CONDITION OF THE UPPER ATMOSPHERE BASED ON THE ELECTRON DENSITY PROFILES OF THE F REGION

1966 ◽  
Vol 44 (1) ◽  
pp. 175-205 ◽  
Author(s):  
Nobuo Matuura
Keyword(s):  
Electron Density ◽  
Molecular Nitrogen ◽  
Dissociative Recombination ◽  
Atmospheric Parameters ◽  
Density Profiles ◽  
Density Distributions ◽  
F Region ◽  
Recombination Processes ◽  
Ion Production ◽  
Electron Density Profiles

The upper atmospheric parameters that control the daytime electron density distributions in the F1 region have been determined with the use of N(h) profiles. The analysis is based on the photochemical equilibrium state in which ion production is given by the ionization of molecular nitrogen and/or molecular oxygen as well as of atomic oxygen, and ionization loss is controlled by charge transfer and dissociative recombination processes. The variations of the upper atmospheric parameters with season, solar activity, and magnetic disturbances have been obtained, and their relations to the behavior of the F1 and F2 layers have been examined.

scholarly journals Self-consistent modelling of the daytime electron density profile in the ionospheric F region

1997 ◽  
Vol 15 (3) ◽  
pp. 314-326 ◽  
Author(s):  
A. Mikhailov ◽  
K. Schlegel
Keyword(s):  
Electron Density ◽  
Molecular Nitrogen ◽  
Molecular Ions ◽  
Ion Composition ◽  
Ion Temperature ◽  
Incoherent Scatter ◽  
Plasma Drift ◽  
F Region ◽  
Self Consistent ◽  
Exospheric Temperature

Abstract. A theoretical self-consistent method for the description of daytime Ne(h) profiles in the ionospheric F region measured by EISCAT is proposed. It is based on the use of a theoretical F-region model and measured electron density, Ne(h), electron, Te(h), and ion temperature, Ti(h), and field-aligned plasma drift Vl(h) profiles. The method describes the observed Ne(h) profile with high accuracy for quiet and disturbed conditions. Two versions of the method are considered: in the first the exospheric temperature Tex is derived from a procedure minimizing [log(Ne(h)obs / Ne(h)cal]2, in the second Tex is deduced from the ion energy conservation in the F region. The method allows us to infer from the incoherent-scatter observations: concentrations of atomic oxygen, [O], molecular oxygen, [O2], molecular nitrogen, [N2] the vertical plasma drift, W, the exospheric temperature. Tex, and the shape parameter S in the neutral temperature profile. The ratio ([O+]/Ne) calculated by the theoretical model is used to correct Te(h), Ti(h) and Ne(h) profiles routinely measured with EISCAT which are known to depend strongly on the actual applied ion-composition model. Such a correction is especially important for geomagnetically disturbed periods when the F region is strongly enriched with molecular ions. We conclude that four of the six thermospheric parameters, namely [O], [N2], W and Tex can be confidently inferred from the EISCAT observations, while the other two derived parameters, [O2] ans S are less reliable. The method can be used for the analysis of long-term (seasonal, solar cycle) as well as for day-to-day variations of the thermospheric parameters and the F-region ion composition using daytime incoherent-scatter observations.

The role of vibrationally excited oxygen and nitrogen in the D and E regions of the ionosphere

1994 ◽  
Vol 12 (10/11) ◽  
pp. 1085-1090 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Anharmonic Oscillator ◽  
Energy Levels ◽  
Vibrationally Excited ◽  
Continuity Equations ◽  
D Region ◽  
E Region ◽  
Excited Oxygen

Abstract. In this paper we present the results of a study of the effect of vibrationally excited oxygen, O*2, and nitrogen, N*2, on the electron density, Ne, and the electron temperature, Te, in the D and E regions. The sources of O*2 are O-atom recombination, the photodissociation of O3, and the reaction of O3 with O at D region altitudes. The first calculations of O*2( j) number densities, Nj, are obtained by solving continuity equations for the models of harmonic and anharmonic oscillator energy levels, j=1-22. It is found that day time values of Nj are less than nighttime values. We also show that the photoionization of O*2 ( j ≥ 11) by Lα-radiation has no influence on the D region Ne. In the nighttime D region the photoionization O*2 ( j ≥ 11) by scattered Lα-radiation can be a new source of O+2. We show that the N*2 and O*2 de-excitation effect on the electron temperature is small in the E region of the ionosphere and cannot explain experimentally observed higher electron temperatures.

scholarly journals On the possible role of cusp/cleft precipitation in the formation of polar-cap patches

1999 ◽  
Vol 17 (10) ◽  
pp. 1298-1305 ◽  
Author(s):  
I. K. Walker ◽  
J. Moen ◽  
L. Kersley ◽  
D. A. Lorentzen
Keyword(s):  
Electron Density ◽  
Source Region ◽  
Convection Flow ◽  
Substantial Part ◽  
Soft Particle ◽  
Polar Cap ◽  
Particle Precipitation ◽  
Flow Measurements ◽  
F Region

Abstract. The work describes experimental observations of enhancements in the electron density of the ionospheric F-region created by cusp/cleft particle precipitation at the dayside entry to the polar-cap convection flow. Measurements by meridian scanning photometer and all-sky camera of optical red-line emissions from aurora are used to identify latitudinally narrow bands of soft-particle precipitation responsible for structured enhancements in electron density determined from images obtained by radio tomography. Two examples are discussed in which the electron density features with size scales and magnitudes commensurate with those of patches are shown to be formed by precipitation at the entry region to the anti-sunward flow. In one case the spectrum of the incoming particles results in ionisation being created, for the most part below 250 km, so that the patch will persist only for minutes after convecting away from the auroral source region. However in a second example, at a time when the plasma density of the solar wind was particularly high, a substantial part of the particle-induced enhancement formed above 250 km. It is suggested that, with the reduced recombination loss in the upper F-region, this structure will retain form as a patch during passage in the anti-sunward flow across the polar cap.Key words. Ionosphere (ionospheric irregularities; particle precipitation; polar ionosphere)

scholarly journals The role of atomic oxygen in the ionospheric E- and F-region behavior

1969 ◽  
Vol 17 (6) ◽  
pp. 1247-1256 ◽  
Author(s):  
J.R. Herman ◽  
S. Chandra
Keyword(s):  
Atomic Oxygen ◽  
F Region

scholarly journals The formation of electron-temperature hot spots in the main ionospheric trough by the internal processes

1996 ◽  
Vol 14 (8) ◽  
pp. 816-825 ◽  
Author(s):  
G. I. Mingaleva ◽  
V. S. Mingalev
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
High Latitude ◽  
Hot Spots ◽  
Electron Gas ◽  
Three Dimensional ◽  
Neutral Atmosphere ◽  
F Region ◽  
Main Ionospheric Trough ◽  
High Latitude Ionosphere

Abstract. A mathematical model of the convecting high-latitude ionosphere is described which produces three-dimensional distributions of electron density, positive-ion velocity and electron and ion temperatures at the F-layer altitudes. The results of simulation of the behaviour of the high-latitude ionosphere, in particular, the heat regime of the F-layer, are presented and analysed. From our study, it was found that electron-temperature hot spots in the main ionospheric trough can arise owing to internal ionospheric processes, and not due to effects of any external causes. Three conditions, to be satisfied simultaneously, are necessary for the formation of the considered electron-temperature hot spots: first, low values of electron density; second, solar illumination of the upper F region and darkness of the lower F region; third, low values of neutral-component densities. These conditions are valid in the main ionospheric trough near the terminator on the nightside when the density of the neutral atmosphere is not high. The physical processes which lead to the formation of the electron-temperature hot spots are the heat transfer from the upper into the lower F region, the reduced heat capacity of electron gas and the weakened cooling of electron gas due to inelastic collisions with neutral atoms and molecules. Also investigated is the influence of seasonal and solar-activity variations on the efficiency of the identified mechanism responsible for the formation of the electron temperature peaks in the main ionospheric trough by the internal processes.

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