scholarly journals Features of short-period variability of total electron content at high and middle latitudes

2021 ◽  
Vol 7 (4) ◽  
pp. 71-78
Author(s):  
Anna Yasyukevich
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Seasonal Variations ◽  
Winter Period ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Period Variability ◽  
Short Period ◽  
Tec Variability

The study presents the results of comparative analysis of features of a short-period (with periods of internal gravity waves) variability of total electron content (TEC) in the ionosphere at middle (Novosibirsk) and high (Norilsk) latitudes over a long period of time (2003–2020). The period analyzed makes it possible to estimate not only diurnal and seasonal variations in the variability, but also its changes within the solar activity cycle. The level of TEC variability is shown to experience pronounced seasonal variations with maxima in winter months. The difference between the level of variability in winter and summer is about two times for Novosibirsk and up to seven times for Norilsk. The variability features a distinct diurnal variation; however, the diurnal dependence at the mid- and high-latitude stations differs significantly. At high latitudes, the level of variability in the winter period strictly depends on solar activity. For the mid-latitude station, there is no clear dependence of variability level on solar activity; in the years of solar maximum, on the contrary, a slight decrease in the variability is observed. In summer, the level of variability at both middle and high latitudes remains practically unchanged and does not depend on solar activity. The main features in the dynamics of variability are shown to be similar at stations located at other longitudes, except for the East American sector. The result obtained suggests that the short-period TEC variability at high latitudes is primarily related to changes in solar activity, but regular variations in the variability at midlatitudes are probably not associated with heliophysical activity. The observed increase in the level of short-period variability in the winter mid-latitude ionosphere is assumed to be related to an increase in wave activity in the stratosphere.

scholarly journals Features of short-period variability of total electron content at high and middle latitudes

2021 ◽  
Vol 7 (4) ◽  
pp. 75-83
Author(s):  
Anna Yasyukevich
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Seasonal Variations ◽  
Winter Period ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Period Variability ◽  
Short Period ◽  
Tec Variability

The study presents the results of comparative analysis of features of a short-period (with periods of internal gravity waves) variability of total electron content (TEC) in the ionosphere at middle (Novosibirsk) and high (Norilsk) latitudes over a long period of time (2003–2020). The period analyzed makes it possible to estimate not only diurnal and seasonal variations in the variability, but also its changes within the solar activity cycle. The level of TEC variability is shown to experience pronounced seasonal variations with maxima in winter months. The difference between the level of variability in winter and summer is about two times for Novosibirsk and up to seven times for Norilsk. The variability features a distinct diurnal variation; however, the diurnal dependence at the mid- and high-latitude stations differs significantly. At high latitudes, the level of variability in the winter period strictly depends on solar activity. For the mid-latitude station, there is no clear dependence of variability level on solar activity; in the years of solar maximum, on the contrary, a slight decrease in the variability is observed. In summer, the level of variability at both middle and high latitudes remains practically unchanged and does not depend on solar activity. The main features in the dynamics of variability are shown to be similar at stations located at other longitudes, except for the East American sector. The result obtained suggests that the short-period TEC variability at high latitudes is primarily related to changes in solar activity, but regular variations in the variability at midlatitudes are probably not associated with heliophysical activity. The observed increase in the level of short-period variability in the winter mid-latitude ionosphere is assumed to be related to an increase in wave activity in the stratosphere.

The electron content of the ionosphere in winter

1961 ◽  
Vol 263 (1313) ◽  
pp. 189-211 ◽  
Keyword(s):  
Total Electron Content ◽  
Faraday Rotation ◽  
Scale Height ◽  
Electron Content ◽  
Radio Waves ◽  
Total Electron ◽  
Neutral Particles ◽  
Short Period ◽  
Wide Scatter ◽  
Magnetic Index

Observations at two closely spaced frequencies of the Faraday rotation of moon-reflected radio waves are described. These measurements have provided accurate values for the total electron content of the ionosphere for many hours on successive days. The observations reported here span a period of one month during the winter of 1960. Short-period fluctuations of the total electron content were observed. These were of about 2 to 3% in amplitude and occurred chiefly during the day-time. The gross shape of the F 2 region as determined by the ratio of the number of electrons above the F 2 peak to the number below was roughly constant during the day, but showed a wide scatter of values at night. The scale height of the ionizable constituent at the F 2 peak was found to be about the same as that of the neutral particles during the day, indicating almost complete mixing. At night, the scale height of the ionizable constituent appeared to increase with the planetary magnetic index K p . It is not possible to say if this was the result of heating of the region or the consequence of electrodynamic drifts.

Equatorial total electron content (TEC) at low and high solar activity

2009 ◽  
Vol 43 (11) ◽  
pp. 1757-1761 ◽  
Author(s):  
O.K. Obrou ◽  
M.N. Mene ◽  
A.T. Kobea ◽  
K.Z. Zaka
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
High Solar Activity ◽  
Electron Content ◽  
Total Electron

scholarly journals Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations

2011 ◽  
Vol 29 (5) ◽  
pp. 865-873 ◽  
Author(s):  
M. P. Natali ◽  
A. Meza
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Principal Component ◽  
High Solar Activity ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Ionospheric Variability ◽  
Low Latitudes ◽  
Sudden Decrease

Abstract. Annual, semiannual and seasonal variations of the Vertical Total Electron Content (VTEC) have been investigated during high solar activity in 2000. In this work we use Global IGS VTEC maps and Principal Component Analysis to study spatial and temporal ionospheric variability. The behavior of VTEC variations at two-hour periods, at noon and at night is analyzed. Particular characteristics associated with each period and the geomagnetic regions are highlighted. The variations at night are smaller than those obtained at noon. At noon it is possible to see patterns of the seasonal variation at high latitude, and patterns of the semiannual anomaly at low latitudes with a slow decrease towards mid latitudes. At night there is no evidence of seasonal or annual anomaly for any region, but it was possible to see the semiannual anomaly at low latitudes with a sudden decrease towards mid latitudes. In general, the semiannual behavior shows March–April equinox at least 40 % higher than September one. Similarities and differences are analyzed also with regard to the same analysis done for a period of low solar activity.

scholarly journals ANALYSES OF TOTAL ELECTRON CONTENT VARIATIONS OVER NORTHERN AND SOUTHERN NIGERIA

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Aghogho Ogwala
Keyword(s):  
Total Electron Content ◽  
Seasonal Variations ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Dual Frequency ◽  
The South ◽  
Total Electron ◽  
The North ◽  
December Solstice ◽  
Latitudinal Difference

Total electron content (TEC) is a parameter of the ionosphere that produces great effect on radio signals. We present the diurnal and seasonal variations of vertical total electron content (vTEC) during the ascending phase of solar cycle 24. A moderate solar activity year (2011) with sunspot number, Rz = 55.7 is used in this study. Total electron content (TEC) deduced from the dual frequency GPS measurements obtained at two ground stations namely: ABUZ (Zaria) with longitude 7.39oE in the north and UNEC (Enugu) with longitude 7.30oE in the south are considered. Both stations are located within the same longitude and has a latitudinal difference of 4.74o in the Nigerian equatorial ionosphere (NEI). Comparison of diurnal and seasonal variations of TEC is carried out for both stations. The diurnal variation of TEC shows a steep increase starting from sunrise, reaching daytime maximum between 13 – 15 LT at UNEC and 14 – 16 LT at ABUZ, then falls to a minimum at sunset. Dawn depression occurred at the same local time of 04 LT at both stations. On a seasonal scale, Pre- and post-midnight values were highest during the Equinoxes, followed by December solstice and least in June Solstice season at ABUZ. Pre- and post-midnight values were also higher during the Equinoxes than the Solstice season at UNEC, although they are about the same range. Also, TEC values are observed to be slightly higher for all hours and seasons at Enugu in the south than Zaria in the north except during March equinox at Zaria where TEC values were higher during the daytime. This implies that there could be little variations in TEC even within the same latitudinal zone.

scholarly journals Global distribution of GPS losses of phase lock and total electron content slips during the 2005 May 15 and the 2003 November 20 magnetic storms

2015 ◽  
Vol 1 (4) ◽  
pp. 58-65 ◽  
Author(s):  
Юрий Ясюкевич ◽  
Yury Yasyukevich ◽  
Эльвира Астафьева ◽  
Elvira Astafyeva ◽  
Илья Живетьев ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Background Level ◽  
Auroral Oval ◽  
Magnetic Storms ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Phase Lock ◽  
Using Data ◽  
Worldwide Network

Using data of worldwide network of GPS receivers we investigated losses of GPS phase lock (LoL) during two strong magnetic storms. At fundamental L1 frequency, LoL density is found to increase up to 0.25 % and at L2 frequency the increase is up to 3 %. This is several times as much compared with the background level. During the 2003 November 20 magnetic storm, the number of total electron content (TEC) slips exceeded the background level ~50 times. During superstorms, the most number of GPS LoL is observed at low and high latitudes. At the same time, the area of numerous TEC slips correspond to auroral oval boundaries.

scholarly journals Strong Interrelation between the Short-Term Variability in the Ionosphere, Upper Mesosphere, and Winter Polar Stratosphere

2020 ◽  
Vol 12 (10) ◽  
pp. 1588
Author(s):  
Anna Yasyukevich ◽  
Irina Medvedeva ◽  
Vera Sivtseva ◽  
Marina Chernigovskaya ◽  
Petr Ammosov ◽  
...  
Keyword(s):  
High Latitude ◽  
Seasonal Variations ◽  
Joint Analysis ◽  
Time Interval ◽  
Electron Content ◽  
Jet Stream ◽  
Short Term ◽  
Total Electron ◽  
Short Period ◽  
Short Term Variability

We perform a joint analysis of short-period (up to several hours) variability in parameters of the ionosphere, the mesosphere, and the stratosphere at mid-latitude, subauroral, and high-latitude points for a long time interval. The study is based on the ionospheric total electron content (TEC) measurements and data on the OH rotational temperature at the mesopause height. We reveal similar seasonal variations in the dynamics of the short-term variability level, both in the ionosphere and the mesosphere. Maximum variability is observed during winter months and it exceeds the values in summer period up to 5–6 times. The revealed dynamics has no explicit relation to the levels of geomagnetic and solar activities. We suggest that the instabilities in the high-velocity stratospheric subauroral winter jet stream may be a source of the recorded variability seasonal variations in the ionosphere and the mesosphere. We propose a new index to estimate a short-term variability in the stratosphere. The index is shown to experience similar regular seasonal variations with a maximum during winter months. We show a clear correlation between the mesosphere/ionosphere variability indices values and the stratosphere disturbance index. The correlation is shown to be higher for the mesosphere variability index as compared with that in the ionosphere, and at the high-latitude point located closer to the jet stream. The obtained results indicate a strong interrelation between the short-period variability in the ionosphere, in the upper mesosphere, and in the subauroral stratosphere. The results contribute to elucidating the basic mechanisms for a vertical coupling between different atmospheric layers.

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