Electron density profiles in the equatorial F-region during evening hours

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.

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Comparative study of electron density from incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum

Annales Geophysicae ◽

10.1007/s00585-001-1630-0 ◽

2000 ◽

Vol 18 (12) ◽

pp. 1630-1634 ◽

Cited By ~ 14

Author(s):

N. K. Sethi ◽

V. K. Pandey

Keyword(s):

Electron Density ◽

Solar Maximum ◽

Iri Model ◽

Bottom Part ◽

Density Profiles ◽

Incoherent Scatter ◽

F Region ◽

Electron Density Profiles ◽

Thickness Parameter ◽

Modelling And Forecasting

Abstract. Arecibo (18.4 N, 66.7 W) incoherent scatter (IS) observations of electron density N(h) are compared with the International Reference Ionosphere (IRI-95) during midday (10–14 h), for summer, winter and equinox, at solar maximum (1981). The N(h) profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option) and the Gulyaeva-B0 thickness (new option). The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option), are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0.Key words: Ionosphere (modelling and forecasting)

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

Canadian Journal of Physics ◽

10.1139/p66-012 ◽

1966 ◽

Vol 44 (1) ◽

pp. 175-205 ◽

Cited By ~ 3

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.

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Search for a thickness parameter for the bottomside ionospheric F-region from incoherent-scatter electron-density profiles

Advances in Space Research ◽

10.1016/0273-1177(87)90272-9 ◽

1987 ◽

Vol 7 (6) ◽

pp. 57-60 ◽

Cited By ~ 11

Author(s):

K.K. Mahajan ◽

R. Kohli

Keyword(s):

Electron Density ◽

Density Profiles ◽

Incoherent Scatter ◽

F Region ◽

Electron Density Profiles ◽

Thickness Parameter

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Plasma line observations from the EISCAT Svalbard Radar during the International Polar Year

Annales Geophysicae ◽

10.5194/angeo-35-1143-2017 ◽

2017 ◽

Vol 35 (5) ◽

pp. 1143-1149

Author(s):

Nickolay Ivchenko ◽

Nicola M. Schlatter ◽

Hanna Dahlgren ◽

Yasunobu Ogawa ◽

Yuka Sato ◽

...

Keyword(s):

Electron Density ◽

Time Of Day ◽

Fast Method ◽

International Polar Year ◽

Density Profiles ◽

Incoherent Scatter ◽

F Region ◽

Plasma Line ◽

International Polar ◽

Electron Density Profiles

Abstract. Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. When detectable the plasma line gives accurate measure of the electron density and can potentially be used to constrain incoherent scatter estimates of electron temperature. We investigate the statistical occurrence of plasma line enhancements with data from the high-latitude EISCAT Svalbard Radar obtained during the International Polar Year (IPY, 2007–2008). A computationally fast method was implemented to recover the range-frequency dependence of the plasma line. Plasma line backscatter strength strongly depends on time of day, season, altitude, and geomagnetic activity, and the backscatter is detectable in 22.6 % of the total measurements during the IPY. As expected, maximum detection is achieved when photo-electrons due to the Sun's EUV radiation are present. During summer daytime hours the occurrence of detectable plasma lines at altitudes below the F-region peak is up to 90 %. During wintertime the occurrence is a few percent. Electron density profiles recovered from the plasma line show great detail of density variations in height and time. For example, effects of inertial gravity waves on the electron density are observed.

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

10.5194/angeo-2018-3 ◽

2018 ◽

Author(s):

Navin Parihar ◽

Sandro M. 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 nm and OI 630.0 nm nightglow emissions were carried at a low latitude station, Allahabad (25.5º N, 81.9º E, geomag. lat. ~16.30º N), located near the crest of Appleton anomaly in India during September–December 2009. This study attempts to examine the behaviour of 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, electron density maximum (Nm) and its height (hmF2) of the F-layer have been derived from the information of two calibrated intensities. Nightglow derived Nm and hmF2 were in reasonable agreement with few measurements reported earlier. Nm and hmF2 were used to study the behaviour of the F-region over Allahabad on the limited number of nights. Nocturnal variation of Nm showed the signatures of the retreat of equatorial ionization anomaly (EIA) and mid-night temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves having period 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 the ionospheric processes.

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