Comparison of electron concentrations in the ionospheric E-layer maximum in spring conditions obtained by calculations and Moscow ionosonde measurements

Large-scale ionospheric disturbances were observed in France by HF ionospheric sounding measurements during major magnetic storms, specially during the March 13–14, 1989 storm. The experiment used a network of four stations (one continuous wave transmitting station and three receiving stations) to determine the horizontal component of the phase velocity of the travelling disturbances by triangulation. The vertical component was determined by using several frequencies on one of the links and ionograms indicated overall ionospheric changes every 30 min. During the first diurnal phase of the March 13, 1989 magnetic storm, four large oscillations of the F2-layer critical frequency f0F2 were observed. During the first and second f0F2 decreases, a dense F1 region, revealing strong compositional changes in the lower thermosphere, modulated the oscillations and contributed to a F2-region virtual height increase to above 800 km. The Doppler measurements at 150–180 km detected only magnetic pulsations and southward travelling acoustic waves. The large-scale disturbances reached the altitude of the Doppler measurements 30 min after the fourth f0F2 peak, with a rapid upward and downward plasma drift of 250 m s−1. This disturbance moved to the southwest at 860 m s−1. During the March 13–14 nocturnal phase an auroral type Es appeared, formed by irregularities extending over 800 km. The ionosphere almost disappeared at 0330 UT and a low-density spread F was observed until the sunrise; the Doppler links were interrupted all the night. During the March 14 morning phase, southward travelling acoustic waves were observed and the F region seemed to be limited to the F1 region. This is probably an effect of the extreme G condition, arising from a decrease of the F2-layer maximum below the F1-layer maximum. The principal features of this storm are compared with those of two other storms on April 12, 1990 and August 14–15, 1989.

Download Full-text

STATISTICS OF VARIATION RANGE OF F2- LAYER MAXIMUM HEIGHT OF THE IONOSPHERE

NEWS OF THE NATIONAL ACADEMY OF SCIENCES OF THE REPUBLIC OF KAZAKHSTAN ◽

10.32014/2019.2518-1726.51 ◽

2019 ◽

Vol 4 (326) ◽

pp. 129-134

Author(s):

Arthur Fedorovich Yakovets ◽

◽

Arezu Jahanshir ◽

Galina Ivanovna Gordienko ◽

Beybit Tenelovich Zhumabayev ◽

...

Keyword(s):

Maximum Height ◽

Layer Maximum ◽

Variation Range

Download Full-text

Properties of the F2-layer maximum density variability over Irkutsk under different levels of the solar and geomagnetic activity

Solnechno-Zemnaya Fizika ◽

10.12737/6558 ◽

2015 ◽

Vol 1 (1) ◽

pp. 56-62 ◽

Cited By ~ 5

Author(s):

Марат Деминов ◽

Marat Deminov ◽

Галина Деминова ◽

Galina Deminova ◽

Гелий Жеребцов ◽

...

Keyword(s):

Geomagnetic Activity ◽

Maximum Density ◽

Activity Level ◽

Solar Activity Level ◽

Absolute Value ◽

Layer Maximum ◽

First Approximation ◽

Hourly Data ◽

General Dispersion ◽

Different Levels

Using hourly data (1958–1992) from Irkutsk ionosonde station, we analyzed properties of variability of the F2-layer maximum density, Nm, under different levels of the solar and geomagnetic activity. The standard deviation s(x) of Nm fluctuations relative to the quiet level (x=(Nm/Nm0–1)·100 %), and the average shift of these fluctuations x-ave were used as characteristics of this variability. For this purpose, the empirical model of the F2-layer maximum density for quiet magnetic conditions, Nm0, was constructed. The Nm variability was found to depend weakly on the solar activity level; in the first approximation, this dependence can be neglected. The Nm variability dependence on geomagnetic activity is among the principal ones, along with the dependences on local time and season. In general, dispersion of Nm fluctuations under quiet conditions is smaller than that during the periods of high geomagnetic activity. During the periods of high geomagnetic activity, however, the dispersion does not increase with the further growth of this activity, while the absolute value of shift x-ave (which is mainly negative under high geomagnetic activity) still increases with growing geomagnetic activity. As a result, if this activity is high enough, the condition |x-ave|>|s(x)| can be fulfilled.

Download Full-text