scholarly journals On the link between the topside ionospheric effective scale height and the plasma ambipolar diffusion, theory and preliminary results

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alessio Pignalberi ◽  
Michael Pezzopane ◽  
Bruno Nava ◽  
Pierdavide Coïsson
Keyword(s):  
Electron Density ◽  
Diffusion Theory ◽  
Vertical Gradient ◽  
Electron Density Profile ◽  
Ambipolar Diffusion ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Effective Parameters ◽  
Analytical Functions ◽  
Vertical Scale

Abstract Over the years, an amount of models relying on effective parameters were implemented in the challenging issue of the topside ionosphere description. These models are based on different analytical functions, but all of them depend on a parameter called effective scale height, that is deduced from topside electron density measurements. As their names state, they are effective in reproducing the topside electron density profile only when applied to the analytical function used to derive them. Then, in principle, they do not have any physical meaning. It is the goal of this paper to mathematically link the effective scale height modeled through the Epstein layer to the vertical scale height theoretically deduced from the plasma ambipolar diffusion theory. Firstly, effective and theoretical scale heights are linked through a mathematical relation by showing that they tend to each other in the topside ionosphere. Secondly, their connection is preliminarily demonstrated by calculating effective scale height values from the entire COSMIC/FORMOSAT-3 radio occultation dataset. Thirdly, a possible connection between the vertical gradient of the topside scale height (as obtained by COSMIC/FORMOSAT-3 satellites) and the electron temperature (as obtained by ESA Swarm B satellite) is studied by highlighting corresponding similarities in the diurnal, seasonal, solar activity, and latitudinal variability.

New topside ionosphere model based on Vary-Chap function using radio occultation and topside sounder data

2020 ◽  
Author(s):  
Mengjie Wu
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Satellite System ◽  
Electron Density Profile ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Ionosphere Model ◽  
Ionospheric Models ◽  
Electron Density Profiles ◽  
Global Navigation Satellite

<p><span>The Global Navigation Satellite System (GNSS) radio occultation and topside sounder provide materials for the validation of a mathematical description of the topside ionosphere up to satellite altitude. An attempt to represent the topside electron density profile is using α-Chapman function with a continuously varying scale height. In this study, the Vary-Chap scale height profiles are obtained based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) electron density profiles from 1 January 2008 to 31 December 2013 and fitted by a shape function composed of two weighted patterns representing the ion and electron contributions of lower and higher altitudes. The topside profiles of ISIS-1 data are used to define the transition height of different ions. The associated fitting parameters are analyzed to reveal their temporal and spatial features and variations along with enhancement of solar activity. Their prominent dependence on latitudes, longitudes, the local time, the season, and the solar cycle facilitates modeling of the Vary-Chap scale height in constructing empirical topside ionospheric models.</span></p>

scholarly journals Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment

2007 ◽  
Vol 25 (9) ◽  
pp. 2019-2027 ◽  
Author(s):  
L. Liu ◽  
W. Wan ◽  
M.-L. Zhang ◽  
B. Ning ◽  
S.-R. Zhang ◽  
...  
Keyword(s):  
Electron Density ◽  
Thermal Structure ◽  
Plasma Temperature ◽  
Scale Height ◽  
Incoherent Scatter Radar ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
Vertical Scale ◽  
Electron Density Profiles

Abstract. A 30-day incoherent scatter radar (ISR) experiment was conducted at Millstone Hill (288.5° E, 42.6° N) from 4 October to 4 November 2002. The altitude profiles of electron density Ne, ion and electron temperature (Ti and Te), and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height Hp, vertical scale height VSH, Chapman scale height Hm, ion velocity, and the relative altitude gradient of plasma temperature (dTp/dh)/Tp, as well as the F2 layer electron density (NmF2) and height (hmF2). These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed conditions. Results show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions, while the main feature of the scale heights, as well as other parameters, deviated significantly from their median behaviors under disturbed conditions. The enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights, as well as the shape of the topside electron density profiles. Over Millstone Hill, the diurnal behaviors of the median VSH and Hm are very similar to each other and are not so tightly correlated with that of the plasma scale height Hp or the plasma temperature. The present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and dynamics. The values of VSH/Hp tend to decrease as (dTp/dh)/Tp becomes larger or the dynamic processes become enhanced.

scholarly journals Topside ionospheric vertical electron density profile reconstruction using GPS and ionosonde data: possibilities for South Africa

2011 ◽  
Vol 29 (2) ◽  
pp. 229-236 ◽  
Author(s):  
P. Sibanda ◽  
L. A. McKinnell
Keyword(s):  
South Africa ◽  
Electron Density ◽  
Geographic Location ◽  
Electron Density Profile ◽  
Empirical Modeling ◽  
Topside Ionosphere ◽  
Electron Content ◽  
Total Electron ◽  
Gps Tec ◽  
Profile Reconstruction

Abstract. Successful empirical modeling of the topside ionosphere relies on the availability of good quality measured data. The Alouette, ISIS and Intercosmos-19 satellite missions provided large amounts of topside sounder data, but with limited coverage of relevant geophysical conditions (e.g., geographic location, diurnal, seasonal and solar activity) by each individual mission. Recently, methods for inferring the electron density distribution in the topside ionosphere from Global Positioning System (GPS)-based total electron content (TEC) measurements have been developed. This study is focused on the modeling efforts in South Africa and presents the implementation of a technique for reconstructing the topside ionospheric electron density (Ne) using a combination of GPS-TEC and ionosonde measurements and empirically obtained Upper Transition Height (UTH). The technique produces reasonable profiles as determined by the global models already in operation. With the added advantage that the constructed profiles are tied to reliable measured GPS-TEC and the empirically determined upper transition height, the technique offers a higher level of confidence in the resulting Ne profiles.

scholarly journals Electron Densities and Scale Heights in the Mid-latitude Topside Ionosphere

1967 ◽  
Vol 20 (4) ◽  
pp. 401 ◽  
Author(s):  
PL Dyson
Keyword(s):  
Electron Density ◽  
Northern Hemisphere ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Electron Densities ◽  
Night Time ◽  
Transition Level ◽  
Latitude Region ◽  
Latitudinal Variations

The diurnal and latitudinal variations of electron density and plasma scale height in the topside ionosphere during summer and winter have been calculated from Alouette I ionograms recorded at Woomera. The electron density behaviour is anomalous in that the winter night-time values are generally as large or larger than those occurring during the day. At heights near 1000 km the winter night-time values are greater than those for night-time summer. The behaviour of the scale height is very similar to that reported by others for the mid-latitude region of the northern hemisphere and implies that at night-time the transition level from 0+ to lighter ions occurs at heights of about 550 km in summer and 500 km in winter.

scholarly journals Comparison of the characteristics of ionospheric parameters obtained from FORMOSAT-3 and digisonde over Ascension Island

2013 ◽  
Vol 31 (5) ◽  
pp. 787-794 ◽  
Author(s):  
Y. J. Chuo ◽  
C. C. Lee ◽  
W. S. Chen ◽  
B. W. Reinisch
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Peak Height ◽  
Electron Density Profile ◽  
Scale Height ◽  
Activity Period ◽  
Iri Model ◽  
Ascension Island ◽  
Seasonal And Diurnal Variations ◽  
Electron Density Profiles

Abstract. Electron density profile data obtained from the FORMOSAT-3 radio occultation (RO) measurements over Ascension Island are used to study the bottomside thickness parameter B0 in the International Reference Ionosphere (IRI) model, scale height around the F region peak height, and other F2 region parameters. The RO data were collected when the radio occultation occurred at Ascension Island (345.6° E, 8.0° S) during the solar minimum activity period from May 2006 to April 2008. Results show that the B0 values are in moderate agreement with the ground-based observations in the equinox period (correlation coefficient r = 0.682) and winter (r = 0.570), with a strong correlation in summer (r = 0.750). The seasonal and diurnal variations in B0 over Ascension Island show peak values during the daytime and in winter. In addition, the B0 values were underestimated and overestimated in the RO measurements during the daytime and nighttime, respectively. Moreover, the comparison of scale heights shows that scale heights obtained from the retrieved data and digisonde observations are weakly correlation in all three seasons. Furthermore, although the effective scale height (HT) values were reverse of those obtained from the RO measurements and are higher during the nighttime than in the daytime, they are in good agreement with those from ground-based observations. This paper also provides a comprehensive discussion of the effect of the asymmetric ionospheric electron density profiles on RO measurements.

Estimation of the electron density profile in the D region from rocket measurement of VLF signals from a ground based transmitter

1981 ◽  
Vol 64 (11) ◽  
pp. 68-74
Author(s):  
Isamu Nagano ◽  
Masayoshi Mambo ◽  
Tetsuo Fukami ◽  
Koji Namba ◽  
Iwane Kimura
Keyword(s):  
Electron Density ◽  
Density Profile ◽  
Electron Density Profile ◽  
Rocket Measurement ◽  
D Region

scholarly journals Looking for a proxy of the ionospheric turbulence with Swarm data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paola De Michelis ◽  
Giuseppe Consolini ◽  
Alessio Pignalberi ◽  
Roberta Tozzi ◽  
Igino Coco ◽  
...  
Keyword(s):  
Electron Density ◽  
Geomagnetic Activity ◽  
Density Fluctuations ◽  
Rate Of Change ◽  
Topside Ionosphere ◽  
Joint Probability Distribution ◽  
Activity Levels ◽  
Scaling Exponents ◽  
Electron Density Fluctuations ◽  
Scaling Features

AbstractThe present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE < 50 nT) and active (AE > 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude—magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy.

scholarly journals Radial density profile and stability of capillary discharge plasma waveguides of lengths up to 40 cm

2021 ◽  
Vol 9 ◽  
Author(s):  
M. Turner ◽  
A. J. Gonsalves ◽  
S. S. Bulanov ◽  
C. Benedetti ◽  
N. A. Bobrova ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Electron Density ◽  
Density Profile ◽  
Pulse Propagation ◽  
Spot Size ◽  
Capillary Discharge ◽  
Electron Density Profile ◽  
Plasma Waveguide ◽  
Wakefield Acceleration ◽  
Plasma Wakefield

Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters of 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm and lengths of 9 to 40 cm. To the best of the authors’ knowledge, 40 cm is the longest discharge capillary plasma waveguide to date. This length is important for $\ge$ 10 GeV electron energy gain in a single laser-driven plasma wakefield acceleration stage. Evaluation of waveguide parameter variations showed that their focusing strength was stable and reproducible to $<0.2$ % and their average on-axis plasma electron density to $<1$ %. These variations explain only a small fraction of laser-driven plasma wakefield acceleration electron bunch variations observed in experiments to date. Measurements of laser pulse centroid oscillations revealed that the radial channel profile rises faster than parabolic and is in excellent agreement with magnetohydrodynamic simulation results. We show that the effects of non-parabolic contributions on Gaussian pulse propagation were negligible when the pulse was approximately matched to the channel. However, they affected pulse propagation for a non-matched configuration in which the waveguide was used as a plasma telescope to change the focused laser pulse spot size.

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