Statistical characteristics of geomagnetic storms in the 24th cycle of solar activity

Mid-latitude trough (MIT) is the distinct structure observed in Earth&#8217;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.&#160;Based on the observations gathered by DEMETER data between 2005 and 2010 years&#160; 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&#160; described by a set of different parameters.

Download Full-text

Study of Geomagnetic Storms and Solar Flares in the Years of Increasing Solar Activity, Cycles 19 and 20 (1955-1957, 1965-1968),

10.21236/ada065261 ◽

1978 ◽

Cited By ~ 2

Author(s):

H. W. Dodson-Prince ◽

E. R. Hedeman ◽

O. C. Mohler

Keyword(s):

Solar Activity ◽

Solar Flares ◽

Geomagnetic Storms ◽

Activity Cycles ◽

Solar Activity Cycles

Download Full-text

Diurnal Variations in the Statistical Characteristics of the Variability of the Midlatitude NmF2 during Quiet Geomagnetic Conditions at Low Solar Activity

Geomagnetism and Aeronomy ◽

10.1134/s0016793219040133 ◽

2019 ◽

Vol 59 (5) ◽

pp. 593-605

Author(s):

A. V. Pavlov ◽

N. M. Pavlova

Keyword(s):

Solar Activity ◽

Diurnal Variations ◽

Statistical Characteristics

Download Full-text

Storm time spatial variations in TEC during moderate geomagnetic storms in extremely low solar activity conditions (2007–2009) over Indian region

Advances in Space Research ◽

10.1016/j.asr.2013.03.006 ◽

2013 ◽

Vol 52 (1) ◽

pp. 158-176 ◽

Cited By ~ 8

Author(s):

Surendra Sunda ◽

B.M. Vyas ◽

P.V. Khekale

Keyword(s):

Solar Activity ◽

Geomagnetic Storms ◽

Spatial Variations ◽

Indian Region

Download Full-text

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

10.5194/egusphere-egu2020-9715 ◽

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

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.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&#160; 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.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%.

Download Full-text

On the variations of the thermospheric structure

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1965.0236 ◽

1965 ◽

Vol 288 (1415) ◽

pp. 493-509 ◽

Cited By ~ 6

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.

Download Full-text