Comparison of F-region electron density observations by satellite radio tomography and incoherent scatter methods

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.

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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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Statistical Analysis of the Electron Density Gradients in the Polar Cap F Region Using the Resolute Bay Incoherent Scatter Radar North

Journal of Geophysical Research Space Physics ◽

10.1029/2017ja025156 ◽

2018 ◽

Vol 123 (5) ◽

pp. 4066-4079 ◽

Cited By ~ 3

Author(s):

Victoriya V. Forsythe ◽

Roman A. Makarevich

Keyword(s):

Statistical Analysis ◽

Electron Density ◽

Density Gradients ◽

Polar Cap ◽

Incoherent Scatter Radar ◽

Incoherent Scatter ◽

F Region ◽

Scatter Radar ◽

Resolute Bay

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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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Self-consistent modelling of the daytime electron density profile in the ionospheric F region

Annales Geophysicae ◽

10.1007/s00585-997-0314-9 ◽

1997 ◽

Vol 15 (3) ◽

pp. 314-326 ◽

Cited By ~ 9

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.

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Comparison of F-region electron density observations by satellite radio tomography and incoherent scatter methods

Annales Geophysicae ◽

10.1007/s00585-996-1422-7 ◽

1996 ◽

Vol 14 (12) ◽

pp. 1422-1428 ◽

Cited By ~ 5

Author(s):

T. Nygrén ◽

M. Markkanen ◽

M. Lehtinen ◽

E. D. Tereshchenko ◽

B. Z. Khudukon ◽

...

Keyword(s):

Electron Density ◽

Meridional Plane ◽

Incoherent Scatter ◽

The North ◽

F Region ◽

First Results ◽

The Difference ◽

A Chain ◽

Set Up ◽

Uhf Radar

Abstract. In November 1995 a campaign of satellite radiotomography supported by the EISCAT incoherent scatter radar and several other instruments was arranged in Scandinavia. A chain of four satellite receivers extending from the north of Norway to the south of Finland was installed approximately along a geomagnetic meridian. The receivers carried out difference Doppler measurements using signals from satellites flying along the chain. The EISCAT UHF radar was simultaneously operational with its beam swinging either in geomagnetic or in geographic meridional plane. With this experimental set-up latitudinal scans of F-region electron density are obtained both from the radar observations and by tomographic inversion of the phase observations given by the difference Doppler experiment. This paper shows the first results of the campaign and compares the electron densities given by the two methods.

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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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