Solar activity dependence of ionospheric electron content and slab thickness using different solar indices

1993 ◽  
Vol 140 (4) ◽  
pp. 721-728 ◽  
Author(s):  
R. S. Dabas ◽  
D. R. Lakshmi ◽  
B. M. Reddy
Keyword(s):  
Solar Activity ◽  
Slab Thickness ◽  
Electron Content ◽  
Ionospheric Electron Content ◽  
Activity Dependence

scholarly journals Winter anomaly in NmF2 and TEC: when and where it can occur

2018 ◽  
Vol 8 ◽  
pp. A45 ◽  
Author(s):  
Yury V. Yasyukevich ◽  
Anna S. Yasyukevich ◽  
Konstantin G. Ratovsky ◽  
Maxim V. Klimenko ◽  
Vladimir V. Klimenko ◽  
...  
Keyword(s):  
Solar Activity ◽  
Meridional Wind ◽  
Global Scale ◽  
Activity Level ◽  
Electron Content ◽  
Intensity Increase ◽  
Total Electron ◽  
Solar Activity Level ◽  
Winter Anomaly ◽  
Activity Dependence

For the first time, by using a regression procedure, we analyzed the solar activity dependence of the winter anomaly intensity in the ionospheric F2-layer peak electron density (Nm F2) and in the Total Electron Content (TEC) on a global scale. We used the data from global ionospheric maps for 1998–2015, from GPS radio occultation observations with COSMIC, CHAMP, and GRACE satellites for 2001–2015, and ground-based ionosonde data. The fundamental features of the winter anomaly in Nm F2 and in TEC (spatial distribution and solar activity dependence) are similar for these parameters. We determined the regions, where the winter anomaly may be observed in principle, and the solar activity level, at which the winter anomaly may be recorded in different sectors. A growth in geomagnetic disturbance or in the solar activity level is shown to facilitate the winter anomaly intensity increase. Longitudinal variations in the winter anomaly intensity do not conform partly to the generally accepted Rishbeth theory. We consider the obtained results in the context of spatial and solar cycle variations in O/N2 ratio and thermospheric meridional wind. Additionally, we briefly discuss different definitions of the winter anomaly.

SATELLITE TRANSMISSION MEASUREMENTS OF IONOSPHERIC ELECTRON CONTENT AT A TIME OF LOW SOLAR ACTIVITY

1965 ◽  
Vol 43 (6) ◽  
pp. 1059-1067 ◽  
Author(s):  
G. F. Lyon
Keyword(s):  
Solar Activity ◽  
Solar Zenith Angle ◽  
Activity Index ◽  
Magnetic Activity ◽  
Electron Content ◽  
Horizontal Gradients ◽  
Rotation Method ◽  
Ionospheric Electron Content ◽  
Transmission Measurements ◽  
Satellite Transmission

The results of observations of the 54-Mc/s signal from Transit IVA (1961 Omicron 1) during a 12-month period are presented. Total columnar electron content measurements are made by the differential Faraday rotation method. It is shown that the electron content is inversely dependent upon the magnetic-activity index during the summer months but not during the winter. The presence of horizontal gradients in content is sometimes indicated. It is also found that the variation of electron content with solar zenith angle indicates an ionosphere approximating an ideal Chapman layer.

scholarly journals Long term ionospheric electron content variations over Delhi

2000 ◽  
Vol 18 (12) ◽  
pp. 1635-1644 ◽  
Author(s):  
J. K. Gupta ◽  
L. Singh
Keyword(s):  
Solar Activity ◽  
Magnetic Activity ◽  
High Solar Activity ◽  
Electron Content ◽  
Solar Cycles ◽  
Positive Correlation ◽  
Radio Science ◽  
Ionospheric Physics ◽  
Winter Anomaly ◽  
Ionospheric Electron Content

Abstract. Ionospheric electron content (IEC) observed at Delhi (geographic co-ordinates: 28.63°N, 77.22°E; geomagnetic co-ordinates: 19.08°N, 148.91°E; dip Latitude 24.8°N), India, for the period 1975–80 and 1986–89 belonging to an ascending phase of solar activity during first halves of solar cycles 21 and 22 respectively have been used to study the diurnal, seasonal, solar and magnetic activity variations. The diurnal variation of seasonal mean of IEC on quiet days shows a secondary peak comparable to the daytime peak in equinox and winter in high solar activity. IECmax (daytime maximum value of IEC, one per day) shows winter anomaly only during high solar activity at Delhi. Further, IECmax shows positive correlation with F10.7 up to about 200 flux units at equinox and 240 units both in winter and summer; for greater F10.7 values, IECmax is substantially constant in all the seasons. IECmax and magnetic activity (Ap) are found to be positively correlated in summer in high solar activity. Winter IECmax shows positive correlation with Ap in low solar activity and negative correlation in high solar activity in both the solar cycles. In equinox IECmax is independent of Ap in both solar cycles in low solar activity. A study of day-to-day variations in IECmax shows single day and alternate day abnormalities, semi-annual and annual variations controlled by the equatorial electrojet strength, and 27-day periodicity attributable to the solar rotation.Key words: Ionosphere (equatorial ionosphere) · Magnetospheric physics (magnetosphere · ionosphere interactions) · Radio science (ionospheric physics)

Ionospheric electron content and equivalent slab thickness in the equatorial region

1975 ◽  
Vol 80 (4) ◽  
pp. 699-701 ◽  
Author(s):  
A. Das Gupta ◽  
S. Basu ◽  
J. N. Bhar ◽  
J. C. Bhattacharyya
Keyword(s):  
Equatorial Region ◽  
Slab Thickness ◽  
Electron Content ◽  
Ionospheric Electron Content

scholarly journals Global equivalent slab thickness model of the Earth’s ionosphere

2021 ◽  
Author(s):  
Norbert Jakowski ◽  
Mohammed Mainul Hoque
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Total Electron Content ◽  
Local Time ◽  
Slab Thickness ◽  
Electron Content ◽  
Night Time ◽  
Total Electron ◽  
First Time ◽  
Model Approach

The shape of the vertical electron density profile is a result of production, loss and transportation of plasma in the Earth’s ionosphere. Therefore, the equivalent slab thickness of the ionosphere that characterizes the width of vertical electron density profiles is an important parameter for a better understanding of ionospheric processes under regular as well as under perturbed conditions. The equivalent slab thickness is defined by the ratio of the vertical total electron content over the peak electron density and is therefore easy to compute by utilizing powerful data sources nowadays available thanks to ground and space based GNSS techniques. Here we use peak electron density data from three low earth orbiting (LEO) satellite missions, namely CHAMP, GRACE and FORMOSAT-3/COSMIC, as well as total electron content data obtained from numerous GNSS ground stations. For the first time, we present a global model of the equivalent slab thickness (Neustrelitz equivalent Slab Thickness Model – NSTM). The model approach is similar to a family of former model approaches successfully applied for Total Electron Content (TEC), peak electron density NmF2 and corresponding height hmF2 at DLR. The model description focuses on an overall view of the behaviour of the equivalent slab thickness as a function of local time, season, geographic/geomagnetic location and solar activity on a global scale. In conclusion, the model agrees quite well with the overall observation data within a RMS range of 70 km. There is generally a good correlation with solar heat input that varies with local time, season and level of solar activity. However, under non-equilibrium conditions, plasma transport processes dominate the behaviour of the equivalent slab thickness. It is assumed that night-time plasmasphere-ionosphere coupling causes enhanced equivalent slab thickness values like the pre-sunrise enhancement. The overall fit provides consistent results with the mid-latitude bulge (MLB) of the equivalent slab thickness, described for the first time in this paper. Furthermore, the model recreates quite well ionospheric anomalies such as the Night-time Winter Anomaly (NWA) which is closely related to the Mid-latitude Summer Night Anomaly (MSNA) like the Weddell Sea Anomaly (WSA) and Okhotsk Sea Anomaly (OSA). Further model improvements can be achieved by using an extended model approach and considering the particular geomagnetic field structure.

Nighttime enhancements in ionospheric electron content: seasonal and solar cycle variation

1995 ◽  
Vol 13 (3) ◽  
pp. 256-261 ◽  
Author(s):  
S. Jain ◽  
S. K. Vijay ◽  
A. K. Gwal ◽  
Y. N. Huang
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Negative Correlation ◽  
Electron Content ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Solar Cycle Variation ◽  
Latitude Station ◽  
Cycle Variation ◽  
Ionospheric Electron Content

Abstract. Various characteristics of anomalous nighttime enhancement in ionospheric electron content (IEC) at Lunping (14.08°N geomagnetic), a station near the crest of the equatorial anomaly, have been presented by considering the IEC data for the 21st solar cycle. Out of a total of 1053 enhancements, 354 occur in pre-midnight and 699 occur in post-midnight hours, which indicates an overall dominance of post-midnight events at Lunping. The occurrence is more frequent during summer, less during the equinox and least during winter months. All the characteristics of the enhancements have seasonal dependencies and they reach their maximum values during summer months. The occurrence of the pre-midnight events show positive and post-midnight events show negative correlation with solar activity. The results have been discussed and compared with those at low-latitude stations in India and Hawaii and at the mid-latitude station, Tokyo.

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