scholarly journals Seasonal and latitudinal variations of the electron density nonmigrating tidal spectrum in the topside ionospheric F region as resolved from CHAMP observations

2014 ◽  
Vol 119 (12) ◽  
Author(s):  
Chao Xiong ◽  
Hermann Lühr ◽  
Claudia Stolle
Keyword(s):  
Electron Density ◽  
F Region ◽  
Latitudinal Variations

Calculation of the electron density of the F region heated by a high-power radio-wave field

1977 ◽  
Vol 20 (12) ◽  
pp. 1267-1270 ◽  
Author(s):  
Yu. A. Ignat'ev ◽  
Z. N. Krotova ◽  
�. E. Mityakova
Keyword(s):  
Radio Wave ◽  
Wave Field ◽  
Electron Density ◽  
High Power ◽  
F Region

scholarly journals An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

2018 ◽  
Vol 36 (3) ◽  
pp. 809-823 ◽  
Author(s):  
Navin Parihar ◽  
Sandro Maria Radicella ◽  
Bruno Nava ◽  
Yenca Olivia Migoya-Orue ◽  
Prabhakar Tiwari ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Satellite Mission ◽  
Low Latitude ◽  
Density Maximum ◽  
Density Profiles ◽  
F Region ◽  
Equatorial Ionization Anomaly ◽  
Low Latitude Ionosphere ◽  
Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 and OI 630.0 nm nightglow emissions were carried at a low-latitude station, Allahabad (25.5° N, 81.9° E; geomag. lat.  ∼  16.30° N), located near the crest of the Appleton anomaly in India during September–December 2009. This report attempts to study the F region of ionosphere using airglow-derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, the electron density maximum (Nm) and its height (hmF2) of the F layer have been derived from the information of two calibrated intensities. Nocturnal variation of Nm showed the signatures of the retreat of the equatorial ionization anomaly (EIA) and the midnight temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves with time periods in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying ionospheric processes.

scholarly journals Study of mid-latitude nighttime enhancement in F-region electron density using tomographic images over the UK

2003 ◽  
Vol 21 (12) ◽  
pp. 2323-2328 ◽  
Author(s):  
R. S. Dabas ◽  
L. Kersley
Keyword(s):  
Electron Density ◽  
Magnetic Activity ◽  
Electron Content ◽  
Equatorial Anomaly ◽  
Tomographic Images ◽  
F Region ◽  
Electron Density Gradient ◽  
Modeling And Forecasting ◽  
Ionospheric Electron Content ◽  
The Uk

Abstract. Nighttime enhancements in ionospheric electron content (IEC)/peak electron density (NmF2) have been studied by various workers in the equatorial anomaly and mid-latitude regions. Such studies give an idea about their enhancement over that location only. In the present study tomographic images over the UK, which give a latitudinal versus height distributions of ionospheric electron density in a much wider area, have been used to study the anomalous increases in nighttime F-region electron density at mid-latitudes. From the analysis of four seasonal representative months (November 1997, March, June and October 1998) data it was noted that the majority of the cases of nighttime enhancements were observed after local midnight, with a maximum between 03:00–04:00 LT in the month of November 1997. Enhancements were observed mostly between 45–50° N latitudes, and their positions are not affected by magnetic activity (Kp ) variations, whereas the separation between the mid-latitude trough and enhancement decreases with increases in magnetic activity. This finding shows that only the trough moves equatorward with the increase in magnetic activity. It is also noted that the electron density gradient from the trough to the enhancement increases with an increase in Kp. Results are discussed in terms of downward plasma transport from the protonosphere to the ionosphere and the nighttime neutral winds.Key words. Ionosphere (mid-latitude ionosphere; modeling and forecasting; instruments and techniques)

scholarly journals Observing the north polar ionosphere on 30 October 2003 by GPS imaging and IS radars

2006 ◽  
Vol 24 (1) ◽  
pp. 107-113 ◽  
Author(s):  
C. Stolle ◽  
J. Lilensten ◽  
S. Schlüter ◽  
Ch. Jacobi ◽  
M. Rietveld ◽  
...  
Keyword(s):  
Time Series ◽  
Electron Density ◽  
Large Scale ◽  
Electron Content ◽  
Polar Ionosphere ◽  
Storm Main Phase ◽  
The North ◽  
F Region ◽  
Longitudinal Band ◽  
North Polar

Abstract. The evening of 30 October 2003 was subject to a major storm main phase. For this time, we combine large-scale electron content maps from GPS imaging with time series of electron density and temperature of two EISCAT radars in Tromsø and Svalbard and the Sondrestrom radar, for observing the north polar ionosphere. The GPS assimilations resulted in the image of the electron content trace of an anti-sunward polar Tongue Of Ionisation (TOI) consecutively to 20:00 UT. In combination with the radar observations we concluded that the TOI persisted during the whole period of continuous southward IMF Bz until about 22:40 UT while its largest extension toward the nightside auroral region was found between 21:00-22:00 UT. A typical F region electron temperature of ~2000 K and the plasma velocity of ~800 ms-1 support its convective origin from the dayside mid-latitudes. Due to the structured appearance of the electron content distribution and the radar electron density time series we believe that discrete plasma patches formed inside the anti-sunward drift pattern. After two large oscillations of the IMF Bz the nightside plasma density was observed to re-enhance after 23:00 UT along a longitudinal band below 70 N. Coinciding electron temperatures of ~2000 K suggest again the convective nature of the plasma, while a modified convection pattern is expected.

scholarly journals The synthesis of travelling ionospheric disturbance (TID) signatures in HF radar observations using ray tracing

2000 ◽  
Vol 18 (1) ◽  
pp. 56-64 ◽  
Author(s):  
A. J. Stocker ◽  
N. F. Arnold ◽  
T. B. Jones
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Ionospheric Disturbance ◽  
Density Perturbation ◽  
Hf Radar ◽  
Ionospheric Disturbances ◽  
F Region ◽  
Abstract Characteristic ◽  
Electron Density Perturbation ◽  
Radar Frequency

Abstract. Characteristic signatures are often observed in HF radar range-time-intensity plots when travelling ionospheric disturbances (TIDs) are present. These signatures, in particular the variation of the F-region skip distance, have been synthesised using a ray tracing model. The magnitude of the skip variation is found to be a function of the peak electron density perturbation associated with the TID and radar frequency. Examination of experimental observations leads to an estimate of the peak electron density perturbation amplitude of around 25% for those TIDs observed by the CUTLASS radar system. The advantage of using the skip variation over the radar return amplitude as an indicator of density perturbation is also discussed. An example of a dual radar frequency experiment has been given. The investigation of the effect of radar frequency on the observations will aid the optimisation of future experiments..Key words. Ionosphere (auroral ionosphere; ionosphere -atmosphere interactions; ionospheric disturbances)

scholarly journals F-region electron density and <i>T<sub>e</sub> / T<sub>i</sub></i> measurements using incoherent scatter power data collected at ALTAIR

2006 ◽  
Vol 24 (5) ◽  
pp. 1333-1342 ◽  
Author(s):  
M. Milla ◽  
E. Kudeki
Keyword(s):  
Electron Density ◽  
Topside Ionosphere ◽  
Low Latitude ◽  
Aspect Angle ◽  
Incoherent Scatter ◽  
F Region ◽  
Regularized Inversion ◽  
The Pacific ◽  
Resolution Electron ◽  
Low Latitude Ionosphere

Abstract. The ALTAIR UHF radar was used in an incoherent scatter experiment to observe the low-latitude ionosphere during the Equis 2 rocket campaign. The measurements provided the first high-resolution electron density maps of the low-latitude D- and E-region in the Pacific sector and also extended into the F-region and topside ionosphere. Although the sampling frequency was well below the Nyquist frequency of F-region returns, we were able to estimate Te / Ti ratio and infer unbiased electron density estimates using a regularized inversion technique described here. The technique exploits magnetic aspect angle dependence of ISR cross-section for Te>Ti.

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.

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