scholarly journals A steady-state F-region model and its use for satellite data analysis

1996 ◽  
Vol 39 (5) ◽  
Author(s):  
S. M. Stankov
Keyword(s):  
Steady State ◽  
Boundary Values ◽  
Satellite Measurements ◽  
F Region ◽  
Dipole Magnetic Field ◽  
Consistent Manner ◽  
Region Model ◽  
Field Lines ◽  
Searching Method ◽  
Upper Ionosphere

A steady-state mathematical model of the Earth's upper ionosphere and plasmasphere is presented. In the model the equations of continuity, momentum, and energy balance for O+, H+, and He+ ions are solved numerically along dipole magnetic field lines. As an extension of the model, a searching method is developed for de- termination of the boundary values in a self-consistent manner. Model results are compared with Atmosphere Explorer satellite measurements.

scholarly journals Modelling the light-ion densities in the ionosphere

1996 ◽  
Vol 39 (6) ◽  
Author(s):  
S. M. Stankov
Keyword(s):  
Steady State ◽  
Theoretical Model ◽  
Satellite Measurements ◽  
Middle Latitudes ◽  
Analytical Functions ◽  
Density Ratios ◽  
Upper Ionosphere ◽  
Existing Data

A steady-state theoretical model is used to obtain variations of the H+/O+ and He+/O+ density ratios in the upper ionosphere at middle latitudes. The model results are compared with the existing data from satellite measurements. Analytical functions are constructed approximating the latitude and altitude variations of these ratios.

Particle balance in a steady state plasma in a dipole magnetic field

2019 ◽  
Vol 1 (4) ◽  
pp. 045005 ◽  
Author(s):  
Anuj Ram Baitha ◽  
Ayesha Nanda ◽  
Sargam Hunjan ◽  
Sudeep Bhattacharjee
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Dipole Magnetic Field ◽  
Particle Balance ◽  
State Plasma

scholarly journals Radar and satellite investigations of equatorial evening vertical drifts and spread <i>F</i>

2015 ◽  
Vol 33 (11) ◽  
pp. 1403-1412 ◽  
Author(s):  
J. M. Smith ◽  
F. S. Rodrigues ◽  
E. R. de Paula
Keyword(s):  
Local Time ◽  
Empirical Model ◽  
Sufficient Condition ◽  
Satellite Measurements ◽  
Equatorial Spread F ◽  
Annual Variability ◽  
F Region ◽  
Plasma Drifts ◽  
Spread F ◽  
Coherent Backscatter

Abstract. We analyzed pre-midnight equatorial F region observations made by the 30 MHz coherent backscatter radar of São Luis, Brazil between August 2010 and February 2012. These measurements were processed, and used to create monthly maps of the echo occurrence as a function of local time and height. The maps show the inter-annual variability associated with equatorial spread F (ESF) occurrence in the Brazilian longitude sector. We also constructed monthly curves of the evening vertical drifts, for the Brazilian sector, using measurements by the ion velocity meter (IVM) onboard the C/NOFS satellite. The IVM evening drifts show a good overall agreement with the Scherliess and Fejer (1999) empirical model. Measured and model drifts show the development of the pre-reversal enhancement (PRE) of the vertical plasma drifts during ESF season. Using joint radar and satellite measurements, we found that evening (18:00–18:30 LT) mean non-negative drifts provide a necessary but not sufficient condition for the occurrence of topside ESF echoes. Evening downward (negative) drifts preceded the absence of topside ESF irregularities.

scholarly journals Mapping of steady-state electric fields and convective drifts in geomagnetic fields – Part 1: Elementary models

2016 ◽  
Vol 34 (1) ◽  
pp. 55-65 ◽  
Author(s):  
A. D. M. Walker ◽  
G. J. Sofko
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Geomagnetic Field ◽  
Geomagnetic Field Models ◽  
Spatial Derivatives ◽  
Field Lines ◽  
The Magnetic Field

Abstract. When studying magnetospheric convection, it is often necessary to map the steady-state electric field, measured at some point on a magnetic field line, to a magnetically conjugate point in the other hemisphere, or the equatorial plane, or at the position of a satellite. Such mapping is relatively easy in a dipole field although the appropriate formulae are not easily accessible. They are derived and reviewed here with some examples. It is not possible to derive such formulae in more realistic geomagnetic field models. A new method is described in this paper for accurate mapping of electric fields along field lines, which can be used for any field model in which the magnetic field and its spatial derivatives can be computed. From the spatial derivatives of the magnetic field three first order differential equations are derived for the components of the normalized element of separation of two closely spaced field lines. These can be integrated along with the magnetic field tracing equations and Faraday's law used to obtain the electric field as a function of distance measured along the magnetic field line. The method is tested in a simple model consisting of a dipole field plus a magnetotail model. The method is shown to be accurate, convenient, and suitable for use with more realistic geomagnetic field models.

scholarly journals Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

2002 ◽  
Vol 20 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
R. Sridharan ◽  
C. V. Devasia ◽  
N. Jyoti ◽  
Diwakar Tiwari ◽  
K. S. Viswanathan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Solar Eclipse ◽  
Equatorial Ionosphere ◽  
Hf Radar ◽  
F Region ◽  
Large Enhancement ◽  
Temporal Structures ◽  
E Region ◽  
Field Lines ◽  
Electric Fields And Currents

Abstract. The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i) the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii) significant increase in h' F immediately following the eclipse and (iii) distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities)

scholarly journals Review of progress in gathering, distributing and using satellite data for activities within COST 238 (PRIME)

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
I. Kutiev ◽  
S. Stankov
Keyword(s):  
Satellite Data ◽  
Satellite Orbit ◽  
Testing Procedure ◽  
Satellite Orbits ◽  
Neutral Atmosphere ◽  
Recombination Rates ◽  
F Region ◽  
Field Lines ◽  
The Given ◽  
To Receive

Recent progress in using the satellite data for various PRIME purposes is briefly presented. The satellite data base is already in operation and contains data of local plasma and neutral atmosphere parameters taken from several ionospheric satellites. A method of tracing the locally measured parameters along the magnetic field lines down to hmF2 is developed using a theoretical F-region code. This method is applied to receive f0F2sat needed to test monthly median and instantaneous mapping methods. In order to reduce the uncertainties arising from the unknown photoionization and recombination rates, f0F2 is calibrated at one point on the satellite orbit with a Vertical Incident (VI) f0F2 and their ratio is then assumed constant along the whole satellite track over the PRIME area. The testing procedure for monthly median maps traces the measured plasma density down to a basic height of 400 km, where individual f0F2sat values are accumulated in every time/subarea bin within the given month, then their median is calibrated with the available medians from the VI ionosonde network. From all available satellite orbits over the PRIME area, 35 of them were found to pass over two VI ionosonde stations. The second station in these orbits was used to check the calculated f0F2sat with the measured VI f0F2. The standard deviation was found to be only 0.15 MHz.

scholarly journals Wave propagation in pulsar magnetospheres

2012 ◽  
Vol 8 (S291) ◽  
pp. 540-542
Author(s):  
Chen Wang ◽  
Dong Lai ◽  
Jinlin Han
Keyword(s):  
Radio Waves ◽  
Plasma Parameters ◽  
Electron Positron ◽  
Transfer Equations ◽  
Propagation Effects ◽  
Consistent Manner ◽  
Physical Effects ◽  
Field Lines ◽  
Polarization Profiles ◽  
The Magnetic Field

AbstractWe study the propagation effects of radio waves in a pulsar magnetosphere, composed of relativistic electron-positron pair plasmas streaming along the magnetic field lines and corotating with the pulsar. We critically examine the various physical effects that can potentially influence the observed wave intensity and polarization. We numerically integrate the transfer equations for wave polarization in the rotating magnetosphere, taking account of all the propagation effects in a self-consistent manner. For typical magnetospheric plasma parameters produced by pair cascade, we find that the observed radio intensity and polarization profiles can be strongly modified by the propagation effects. Some applications of our results are discussed.

scholarly journals Heights of SuperDARN F region echoes estimated from the analysis of HF radio wave propagation

2007 ◽  
Vol 25 (9) ◽  
pp. 1987-1994 ◽  
Author(s):  
A. V. Koustov ◽  
D. André ◽  
E. Turunen ◽  
T. Raito ◽  
S. E. Milan
Keyword(s):  
Electron Density ◽  
Hf Radar ◽  
Field Of View ◽  
Data Set ◽  
Density Distributions ◽  
F Region ◽  
The Earth ◽  
Earth Magnetic Field ◽  
Field Lines ◽  
Radar Wave

Abstract. Tomographic estimates of the electron density altitudinal and latitudinal distribution within the Hankasalmi HF radar field of view are used to predict the expected heights of F region coherent echoes by ray tracing and finding ranges of radar wave orthogonality with the Earth magnetic field lines. The predicted ranges of echoes are compared with radar observations concurrent with the tomographic measurements. Only those events are considered for which the electron density distributions were smooth, the band of F region HF echoes existed at ranges 700–1500 km, and there was a reasonable match between the expected and measured slant ranges of echoes. For a data set comprising of 82 events, the typical height of echoes was found to be 275 km.

Preliminary investigation of the structure of the upper ionosphere as observed by the topside sounder satellite, Alouette

1964 ◽  
Vol 281 (1387) ◽  
pp. 464-487 ◽  
Keyword(s):  
Magnetic Field ◽  
Preliminary Investigation ◽  
Radiation Belts ◽  
Local Times ◽  
Topside Ionosphere ◽  
Equatorial Anomaly ◽  
Electron Distributions ◽  
Field Lines ◽  
Pass Through ◽  
Upper Ionosphere

Results are presented which illustrate the shape of the topside electron distributions at different local times and different latitudes. It is shown that the ionosphere appears to cool and contract during the night. The morphology and diurnal variation of the geomagnetic equatorial anomaly has been investigated; the structure of the equatorial topside ionosphere appears to be determined by the Earth’s magnetic field, and the geomagnetic anomaly is shown to exist in the topside only between 10.00 and 22.00 local time. Deductions about the composition or temperature of the atmosphere are shown to be complicated because diffusion occurs along field lines only and also because the temperature increases with height above ground. The scale height of the electron density distributions is found to increase with latitude, and it is shown that this effect is probably related to an increase of electron temperature with latitude. Five different localized phenomena have been observed in the ionosphere by the topside sounder, and three of these are shown to occur at the latitudes at which the magnetic field lines which pass through the hearts of the three radiation belts enter the Earth’s atmosphere. Other results are presented which also constitute important evidence that particles dumped from the radiation belts may be important sources of heat or ionization in the atmosphere. Observations made at sunrise and also during an eclipse indicate that the effects of electromagnetic movements and/or movements produced by temperature changes are very important in the upper ionosphere.

Ionospheric heating in the F -region

1964 ◽  
Vol 281 (1384) ◽  
pp. 140-149 ◽  
Keyword(s):  
Electron Temperature ◽  
Energy Input ◽  
Particle Flux ◽  
Electron Interaction ◽  
Ion Temperature ◽  
Ionospheric Heating ◽  
F Region ◽  
Field Lines ◽  
Photo Ionization ◽  
Made In

Measurements of electron temperature made in Ariel I have been analyzed to calculate the ionospheric energy input required to maintain the electron temperature above the ion temperature. The results are found to be consistent with the energy input due to photo-ionization in the daytime, provided that allowance is made for the effects of the escaping flux of photoelectrons spiralling upwards along the geomagnetic field lines which impartenergy to the ionosphere by electron-electron interaction. However, it is found that during the night an energy input of particle origin is observed, a close agreement being found between the distribution of energy input and that of the fluxes of low-energy particles observed by Savenko, Shavrin & Pisavenko 1963. The particle flux contributes less than 30% to the heat input in the daytime and its diurnal variation is small.

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