scholarly journals Thermospheric Parameters during Ionospheric G-Conditions

2021 ◽  
Vol 13 (17) ◽  
pp. 3440
Author(s):  
Loredana Perrone ◽  
Andrey V. Mikhailov ◽  
Dario Sabbagh
Keyword(s):  
Atomic Oxygen ◽  
Molecular Nitrogen ◽  
Retrieval Process ◽  
Gas Density ◽  
Oxygen Abundance ◽  
Plasma Drift ◽  
Neutral Gas ◽  
Thermospheric Winds ◽  
First Time ◽  
Exospheric Temperature

For the first time thermospheric parameters (neutral composition, exospheric temperature and vertical plasma drift related to thermospheric winds) have been inferred for ionospheric G-conditions observed with Millstone Hill ISR on 11–13 September 2005; 13 June 2005, and 15 July 2012. The earlier developed method to extract a consistent set of thermospheric parameters from ionospheric observations has been revised to solve the problem in question. In particular CHAMP/STAR and GOCE neutral gas density observations were included into the retrieval process. It was found that G-condition days were distinguished by enhanced exospheric temperature and decreased by ~2 times of the column atomic oxygen abundance in a comparison to quiet reference days, the molecular nitrogen column abundance being practically unchanged. The inferred upward plasma drift corresponds to strong ~90 m/s equatorward thermospheric wind presumably related to strong auroral heating on G-condition days.

Daytime F2-layer positive storm effect at middle and lower latitudes

1995 ◽  
Vol 13 (5) ◽  
pp. 532-540 ◽  
Author(s):  
A. V. Mikhailov ◽  
M. G. Skoblin ◽  
M. Förster
Keyword(s):  
Background Level ◽  
Gas Composition ◽  
Night Time ◽  
Model Calculations ◽  
Plasma Drift ◽  
Neutral Gas ◽  
Storm Effect ◽  
Thermospheric Winds ◽  
Time Sector ◽  
Composition Changes

Abstract. Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as 'night-time' and 'daytime' demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the 'night-time' sector with increased [O] and [N2] absolute concentrations, while (N2/O)storm/(N2/O)quiet\\approx1 at F2-layer heights, are shown to contribute largely to the background NmF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional NmF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the 'daytime' sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N2] concentrations.

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.

Neutral gas composition changes and E×B vertical plasma drift contribution to the daytime equatorial F2-region storm effects

1994 ◽  
Vol 12 (2/3) ◽  
pp. 226-231 ◽  
Author(s):  
A. V. Mikhailov ◽  
M. Förster ◽  
M. G. Skoblin
Keyword(s):  
Atomic Oxygen ◽  
Gas Composition ◽  
Model Calculations ◽  
Storm Effects ◽  
Plasma Drift ◽  
Neutral Gas ◽  
Vertical Drift ◽  
Velocity Changes ◽  
Composition Changes ◽  
Atomic Oxygen Concentration

Abstract. Theoretical model calculations along with ground-based observations from Huancayo ionosonde station and ESRO-4 gas analyzer data, were used to estimate the contribution of neutral gas composition changes and E×B vertical plasma drift to the observed F2-layer storm effects at the geomagnetic equator. Atomic oxygen concentration increase may give the main contribution to the positive NmF2 effect when drift velocity changes are small, but negative storm effects, on the other hand, are related mostly to vertical drift variations.

scholarly journals Mid-Latitude Daytime F2-Layer Disturbance Mechanism under Extremely Low Solar and Geomagnetic Activity in 2008–2009

2021 ◽  
Vol 13 (8) ◽  
pp. 1514
Author(s):  
Andrey V. Mikhailov ◽  
Loredana Perrone ◽  
Anatoly A. Nusinov
Keyword(s):  
Geomagnetic Activity ◽  
Atomic Oxygen ◽  
Eddy Diffusion ◽  
Global Scale ◽  
Original Method ◽  
Sudden Stratospheric Warming ◽  
Oxygen Abundance ◽  
Neutral Gas ◽  
F Region

European near-noontime ionosonde observations were considered during the period of deep solar minimum in 2008–2009 to analyze foF2 perturbations not related to solar and geomagnetic activity. Sudden stratospheric warming (SSWs) events in January 2008 and 2009 were analyzed. An original method was used to retrieve aeronomic parameters from observed electron concentration in the ionospheric F-region. Atomic oxygen was shown to be the main aeronomic parameter responsible both for the observed day-to-day and long-term (during SSWs) foF2 variations. Atomic oxygen rather than neutral temperature mainly controls the decrease of thermospheric neutral gas density in the course of the SSW events. Day-to-day variations of thermospheric circulation and an intensification of eddy diffusion during SSWs are suggested to be the processes changing the atomic oxygen abundance in the upper atmosphere for the periods in question. Recent Global-Scale Observations of the Limb and Disk (GOLD) observations of O/N2 column density confirm the depletion of the atomic oxygen abundance not related to geomagnetic activity during SSWs.

Comet P/Halley neutral gas density profile along the Vega-1 trajectory measured by the Neutral Gas Experiment

1988 ◽  
pp. 360-362 ◽  
Author(s):  
C. C. Curtis ◽  
C. Y. Fan ◽  
K. C. Hsieh ◽  
D. M. Hunten ◽  
W.-H. Ip ◽  
...  
Keyword(s):  
Density Profile ◽  
Gas Density ◽  
Neutral Gas ◽  
Vega 1

The Line of Sight of ϵ Canis Majoris: Depletion and Extent of the Local Cloud

1997 ◽  
Vol 166 ◽  
pp. 161-164
Author(s):  
Cécile Gry ◽  
Olivier Dupin
Keyword(s):  
High Resolution ◽  
Column Density ◽  
Uv Spectra ◽  
Line Of Sight ◽  
Gas Density ◽  
Neutral Gas ◽  
Local Cloud

AbstractWith new high resolution UV spectra of ϵ CMa we show that the gas column density in this sight-line is less than 4 1017 cm−2, that the neutral gas density is less than 10−5 cm−3 after the first 3 parsecs, and that the Local Cloud seems to be almost undepleted and to extend to no more than 0.6 pc in this direction.

1D PIC simulation of microscale breakdown in gaps with a non-uniform background neutral gas density

2013 ◽  
Author(s):  
Chris H. Moore ◽  
Matthew M. Hopkins ◽  
Jeremiah J. Boerner ◽  
Paul S. Crozier ◽  
Lawrence C. Musson ◽  
...  
Keyword(s):  
Gas Density ◽  
Pic Simulation ◽  
Neutral Gas ◽  
Uniform Background

scholarly journals Atomic Oxygen Abundance in Molecular Clouds: Absorption toward Sagittarius B2

2001 ◽  
Vol 561 (2) ◽  
pp. 823-829 ◽  
Author(s):  
D. C. Lis ◽  
Jocelyn Keene ◽  
T. G. Phillips ◽  
P. Schilke ◽  
M. W. Werner ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Atomic Oxygen ◽  
Oxygen Abundance

scholarly journals Vertical circulation and thermospheric composition: a modelling study

1999 ◽  
Vol 17 (6) ◽  
pp. 794-805 ◽  
Author(s):  
H. Rishbeth ◽  
I. C. F. Müller-Wodarg
Keyword(s):  
Concentration Ratio ◽  
Atomic Oxygen ◽  
Molecular Nitrogen ◽  
Three Dimensional ◽  
Atmospheric Composition ◽  
Vertical Circulation ◽  
Energy Inputs ◽  
Composition And Structure ◽  
Vertical Distributions ◽  
Summer Hemisphere

Abstract. The coupled thermosphere-ionosphere-plasmasphere model CTIP is used to study the global three-dimensional circulation and its effect on neutral composition in the midlatitude F-layer. At equinox, the vertical air motion is basically up by day, down by night, and the atomic oxygen/molecular nitrogen [O/N2] concentration ratio is symmetrical about the equator. At solstice there is a summer-to-winter flow of air, with downwelling at subauroral latitudes in winter that produces regions of large [O/N2] ratio. Because the thermospheric circulation is influenced by the high-latitude energy inputs, which are related to the geometry of the Earth's magnetic field, the latitude of the downwelling regions varies with longitude. The downwelling regions give rise to large F2-layer electron densities when they are sunlit, but not when they are in darkness, with implications for the distribution of seasonal and semiannual variations of the F2-layer. It is also found that the vertical distributions of O and N2 may depart appreciably from diffusive equilibrium at heights up to about 160 km, especially in the summer hemisphere where there is strong upwelling. Atmospheric composition and structure (thermosphere · composition and chemistry) · Ionosphere (ionosphere · atmosphere interactions)

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