Latitudinal Dependence of Ionospheric Responses to Some Geomagnetic Storms during Low Solar Activity

2021 ◽  
Vol 61 (3) ◽  
pp. 418-437
Author(s):  
B. W. Joshua ◽  
J. O. Adeniyi ◽  
A. O. Olawepo ◽  
Babatunde Rabiu ◽  
Okoh Daniel ◽  
...  
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Latitudinal Dependence

Solar activity and its impact on the mid-latitude trough during geomagnetic storms

2021 ◽  
Author(s):  
Dorota Przepiórka ◽  
Barbara Matyjasiak ◽  
Agata Chuchra ◽  
Hanna Rothkaehl
Keyword(s):  
Solar Activity ◽  
Geomagnetic Activity ◽  
Evolutionary History ◽  
Geomagnetic Storms ◽  
Magnetic Activity ◽  
Topside Ionosphere ◽  
Auroral Region ◽  
Distinct Structure ◽  
Highly Sensitive ◽  
Rapid Changes

<p>Mid-latitude trough (MIT) is the distinct structure observed in Earth’s ionosphere at high latitudes especially at the nighttimes. The phenomenon is observed at both hemispheres. As it resides at the topside ionosphere in the sub-auroral region, its behaviour and properties are highly sensitive to the solar and geomagnetic activity. Generally as the geomagnetic activity is more pronounced the MIT is observed at lower latitudes, it also deepens and becomes much more distinct in comparison to the low magnetic activity periods. MIT responds as well to the rapid changes in geomagnetic conditions, as are the geomagnetic storms, mainly caused by the CMEs. </p><p>Based on the observations gathered by DEMETER data between 2005 and 2010 years  we present a set of geomagnetic storm cases and how the MIT properties has been changing as the storm evolves. We also discuss how it corresponds to the current solar activity and their evolutionary history  described by a set of different parameters.</p>

Accuracy analysis of global ionospheric maps in relation to their temporal resolution and solar activity level.

2020 ◽  
Author(s):  
Beata Milanowska ◽  
Paweł Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Wojciech Jarmołowski
Keyword(s):  
Solar Activity ◽  
Temporal Resolution ◽  
Geomagnetic Storms ◽  
Activity Level ◽  
Activity Period ◽  
Accuracy Evaluation ◽  
Accuracy Analysis ◽  
International Gnss Service ◽  
Wide Range ◽  
Global Ionospheric Maps

<p>Since 1998 Ionosphere Associate Analysis Centers (IAAC) of the International GNSS Service (IGS) routinely provide global ionosphere maps (GIMs). They are used for a wide range of geophysical applications, including supporting precise positioning and improving space weather analysis. These GIMs are generated by different analysis centers with the use of different modelling techniques. Therefore they have different accuracy levels, which has already been evaluated in several studies. Until 2014 all GIMs were provided with 2-hour temporal resolution, and since 2015 some of the IAACs have started to provide their products with higher resolutions, up to 30 - 60 minutes. Since GIMs have different temporal resolutions, we investigated whether map interval affected their accuracies.</p><p>In this study we carried out IAAC GIM accuracy analysis for years 2014 and 2018, corresponding to high and low solar activity periods, respectively. Since in 2014 IAAC GIMs had 2-hour resolution, we also evaluated UQRG maps supplied with 15-minute interval. For low solar activity period (2018) we evaluated 4 models: CASG, CODG, EMRG and  UQRG. In addition, we studied ionosphere map performance during two selected geomagnetic storms: on 19 February 2014 and 17 March 2015. Our accuracy evaluation was based on GIM-TEC comparisons to differential STEC derived from GNSS data and VTEC derived from altimetry measurements.</p><p>The results show that temporal interval has no significant impact on the overall, annual map RMS during both high and low solar activity periods. However, during geomagnetic storms, when reducing map interval, the map accuracy improves by almost 25%.</p>

scholarly journals On the variations of the thermospheric structure

1965 ◽  
Vol 288 (1415) ◽  
pp. 493-509 ◽  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Phase Shift ◽  
Diurnal Variation ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Atmospheric Temperature ◽  
Atmospheric Density ◽  
Height Range ◽  
Atmospheric Variations

The paper discusses the properties of the different effects which have been found to occur in the thermosphere and some conclusions which can be drawn with regard to the physics of the thermosphere. In the discussion of the diurnal variation the emphasis is on the behaviour of the diurnal amplitude in density during the solar cycle. At the height range between 200 and 300 km the amplitude has remarkably increased with decreasing solar activity. The relation between atmospheric density and temperature and the solar e.u.v. flux and the solar 10.7 cm flux—the latter serving as a convenient parameter—is discussed. The observational results for a phaseshift between the variations in the e.u.v. flux (or 10.7 cm flux) and the correlated variations in atmospheric temperature (or density) lie in the range between 0.5 and 2.3 days. During the solar minimum the atmospheric variations which parallel the 10.7 cm flux are far less pronounced than the variations correlated with geomagnetic activity. The phase shift derived from 45 geomagnetic storms and correlated density changes has been found to be 6 ± 3 (m.e.) h.

scholarly journals Evaluation of automatic ionogram scaling for use in real-time ionospheric density profile specification: Dourbes DGS-256/ARTIST-4 performance

2012 ◽  
Vol 55 (2) ◽  
Author(s):  
Stanimir M. Stankov ◽  
Jean-Claude Jodogne ◽  
Ivan Kutiev ◽  
Koen Stegen ◽  
René Warnant
Keyword(s):  
Solar Activity ◽  
Real Time ◽  
Local Time ◽  
Density Profile ◽  
Error Bounds ◽  
Statistical Evaluation ◽  
Geomagnetic Storms ◽  
Automatic Scaling ◽  
Time Period ◽  
Analysis Error

<p>Statistical evaluation of the Dourbes (4.6˚E, 50.1˚N) digisonde automatic scaling of the more frequently used ionospheric parameters (foF2, foF1, foE, h’F2, h’F, h’E, and M3000F2) was performed using automatically and manually scaled data from the time period of 2002 to 2008. Automatic scaling was provided in 92% to 94% of cases for most characteristics, except for foF1 (81%). In terms of the automatic scaling accuracy, the magnitude of the residual error for foF2 and M3000F2 (automatically minus manually scaled values) varied according to local time, season, and solar activity. Although geomagnetic storms appear to affect the automatic scaling, the overall results for the influence of geomagnetic activity were inconclusive. Based on this analysis, error bounds were determined (95% probability) for each characteristic: foF2 (–0.75,+0.85), foF1(–0.25,+0.35), foE(–0.35,+0.40), h’F2(–68,+67), h’F(–38,+32), h’E(–26,+2), and M3000F2(–0.55,+0.45).</p>

scholarly journals Behavior of Earth Magnetosphere Radius during Strong Geomagnetic Storms

2019 ◽  
Vol 17 (43) ◽  
pp. 103-121
Author(s):  
Mais Mohammed Algbory ◽  
Najat Mohammed Rashed
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Storms ◽  
Upper Atmosphere ◽  
Plasma Stream ◽  
Kinetic Energy Density ◽  
Earth Surface ◽  
Surface Magnetic Field ◽  
Earth Magnetic Field

Magnetosphere is a region of space surrounding Earth magnetic field, the formation of magnetosphere depends on many parameters such as; surface magnetic field of the planet, an ionized plasma stream (solar wind) and the ionization of the planetary upper atmosphere (ionosphere). The main objective of this research is to find the behavior of Earth's magnetosphere radius (Rmp) with respect to the effect of solar wind kinetic energy density (Usw), Earth surface magnetic field (Bo), and the electron density (Ne) of Earth's ionosphere for three years 2016, 2017 and 2018. Also the study provides the effect of solar activity for the same period during strong geomagnetic storms on the behavior of Rmp. From results we found that there are nonlinear relations between the (Rmp) and the three variables (Usw), (Bo) and (Ne). Also we found that during the strong geomagnetic storms there is a reduction in the radius of magnetosphere.

scholarly journals Seasonal features of geomagnetic activity: a study on the solar activity dependence

2021 ◽  
Vol 39 (5) ◽  
pp. 929-943
Author(s):  
Adriane Marques de Souza Franco ◽  
Rajkumar Hajra ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Activity ◽  
Annual Variation ◽  
Geomagnetic Storms ◽  
Solar Wind Speed ◽  
Solar Cycles ◽  
Annual Variations ◽  
Long Duration ◽  
Activity Dependence

Abstract. Seasonal features of geomagnetic activity and their solar-wind–interplanetary drivers are studied using more than five solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1296 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75 863 substorms identified from the SuperMAG AL/SML index from January 1976 to December 2019 and a total of 145 high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events identified using the AE index from January 1975 to December 2017. The occurrence rates of the substorms and geomagnetic storms, including moderate (-50nT≥Dst>-100nT) and intense (-100nT≥Dst>-250nT) storms, exhibit a significant semi-annual variation (periodicity ∼6 months), while the super storms (Dst≤-250 nT) and HILDCAAs do not exhibit any clear seasonal feature. The geomagnetic activity indices Dst and ap exhibit a semi-annual variation, while AE exhibits an annual variation (periodicity ∼1 year). The annual and semi-annual variations are attributed to the annual variation of the solar wind speed Vsw and the semi-annual variation of the coupling function VBs (where V = Vsw, and Bs is the southward component of the interplanetary magnetic field), respectively. We present a detailed analysis of the annual and semi-annual variations and their dependencies on the solar activity cycles separated as the odd, even, weak and strong solar cycles.

scholarly journals Accuracy of Global Ionosphere Maps in Relation to Their Time Interval

2021 ◽  
Vol 13 (18) ◽  
pp. 3552
Author(s):  
Beata Milanowska ◽  
Paweł Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Wojciech Jarmołowski
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
High Solar Activity ◽  
Time Interval ◽  
Electron Content ◽  
Dual Frequency ◽  
Total Electron ◽  
Low Latitudes ◽  
Globally Distributed ◽  
Gnss Observations

Global ionosphere maps (GIMs) representing ionospheric total electron content (TEC) are applicable in many scientific and engineering applications. However, the GIMs provided by seven Ionosphere Associated Analysis Centers (IAACs) are generated with different temporal resolutions and using different modeling techniques. In this study, we focused on the influence of map time interval on the empirical accuracy of these ionospheric products. We investigated performance of the high-resolution GIMs during high (2014) and low (2018) solar activity periods as well as under geomagnetic storms (19 February 2014 and 17 March 2015). In each of the analyzed periods, GIMs were also assessed over different geomagnetic latitudes. For the evaluation, we used direct comparison of GIM-derived slant TEC (STEC) with dual-frequency GNSS observations obtained from 18 globally distributed stations. In order to perform a comprehensive study, we also evaluated GIMs with respect to altimetry-derived vertical TEC (VTEC) obtained from the Jason-2 and Jason-3 satellites. The study confirmed the influence of GIMs time interval on the provided TEC accuracy, which was particularly evident during high solar activity, geomagnetic storms, and also at low latitudes. The results show that 120-min interval contributes significantly to the accuracy degradation, whereas 60-min one is sufficient to maintain TEC accuracy.

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