scholarly journals Statistical study on interplanetary drivers behind intense geomagnetic storms and substorms

2019 ◽  
Vol 3 (5) ◽  
pp. 380-390
Author(s):  
Tian Tian ◽  
◽  
Zheng Chang ◽  
LingFeng Sun ◽  
JunShui Bai ◽  
...  
Keyword(s):  
Statistical Study ◽  
Geomagnetic Storms ◽  
Storms And Substorms

scholarly journals Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

1996 ◽  
Vol 14 (6) ◽  
pp. 608-618 ◽  
Author(s):  
T. Iyemori ◽  
D. R. K. Rao
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Sharp Decrease ◽  
Geomagnetic Disturbance ◽  
Substorm Onset ◽  
Significant Development ◽  
H Index ◽  
Magnetospheric Tail ◽  
Storms And Substorms ◽  
Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

Geomagnetic storms and substorms

1975 ◽  
Vol 13 (3) ◽  
pp. 990 ◽  
Author(s):  
G. L. Siscoe
Keyword(s):  
Geomagnetic Storms ◽  
Storms And Substorms

scholarly journals Ring current influence on auroral electrojet predictions

1999 ◽  
Vol 17 (10) ◽  
pp. 1268-1275 ◽  
Author(s):  
H. Gleisner ◽  
H. Lundstedt
Keyword(s):  
Solar Wind ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Wind Data ◽  
Common Source ◽  
Neural Net ◽  
Operational Forecasting ◽  
Storms And Substorms ◽  
Highly Correlated ◽  
Strong Control

Abstract. Geomagnetic storms and substorms develop under strong control of the solar wind. This is demonstrated by the fact that the geomagnetic activity indices Dst and AE can be predicted from the solar wind alone. A consequence of the strong control by a common source is that substorm and storm indices tend to be highly correlated. However, a part of this correlation is likely to be an effect of internal magnetospheric processes, such as a ring-current modulation of the solar wind-AE relation. The present work extends previous studies of nonlinear AE predictions from the solar wind. It is examined whether the AE predictions are modulated by the Dst index.This is accomplished by comparing neural network predictions from Dst and the solar wind, with predictions from the solar wind alone. Two conclusions are reached: (1) with an optimal set of solar-wind data available, the AE predictions are not markedly improved by the Dst input, but (2) the AE predictions are improved by Dst if less than, or other than, the optimum solar-wind data are available to the net. It appears that the solar wind-AE relation described by an optimized neural net is not significantly modified by the magnetosphere's Dst state. When the solar wind alone is used to predict AE, the correlation between predicted and observed AE is 0.86, while the prediction residual is nearly uncorrelated to Dst. Further, the finding that Dst can partly compensate for missing information on the solar wind, is of potential importance in operational forecasting where gaps in the stream of real time solar-wind data are a common occurrence.Key words. Magnetospheric physics (solar wind · magnetosphere interactions; storms and substorms)

Statistical Study of Geomagnetic Storms during Year 1996-2007

2012 ◽  
Vol 433-440 ◽  
pp. 268-271
Author(s):  
Balveer S. Rathore ◽  
Subhash C. Kaushik ◽  
K.K. Parashar ◽  
Rammohan S. Bhadoria ◽  
Dinesh C. Gupta
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Geomagnetic Storm ◽  
Statistical Study ◽  
Geomagnetic Storms ◽  
Sunspot Cycle ◽  
Solar Wind Plasma ◽  
Strongly Correlated ◽  
Minimum Phase ◽  
Solar Cycle 23

A geomagnetic storm is a global disturbance in Earth’s magnetic field usually occurred due to abnormal conditions in the interplanetary magnetic field (IMF) and solar wind plasma emissions caused by various solar phenomenon. A study of 220 geomagnetic storms associated with disturbance storm time (Dst) decreases of more than -50 nT to -300 nT, observed during 1996-2007, the span of solar cycle 23. We have analyzed and studied them statistically. We find yearly occurrences of geomagnetic storm are strongly correlated with 11-year sunspot cycle, but no significant correlation between the maximum and minimum phase of solar cycle-23 have been found. It is also found that solar cycle-23 is remarkable for occurrence of Intense geomagnetic storm during its declining phase. The detailed results are discussed in this paper.

scholarly journals Geomagnetic Storms and Substorms as Space Weather I nfluence on Atmospheric Electric Field Variations

2018 ◽  
Author(s):  
Natalia G. Kleimenova ◽  
A. Odzimek ◽  
S. Michnowski ◽  
M. Kubicki
Keyword(s):  
Electric Field ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Atmospheric Electric Field ◽  
Storms And Substorms

scholarly journals The equatorial electrojet during geomagnetic storms and substorms

2015 ◽  
Vol 120 (3) ◽  
pp. 2276-2287 ◽  
Author(s):  
Yosuke Yamazaki ◽  
Michael J. Kosch
Keyword(s):  
Geomagnetic Storms ◽  
Equatorial Electrojet ◽  
Storms And Substorms

scholarly journals Association of cusp energetic ions with geomagnetic storms and substorms

2012 ◽  
Vol 30 (12) ◽  
pp. 1633-1643 ◽  
Author(s):  
J. T. Niehof ◽  
S. K. Morley ◽  
R. H. W. Friedel
Keyword(s):  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Energetic Ions ◽  
Significant Dependence ◽  
Substorm Activity ◽  
Storms And Substorms ◽  
Magnetospheric Dynamics ◽  
Substorm Onsets ◽  
Polar Satellite

Abstract. Energetic ions observed in the cusp have been explained as a result of processes within the magnetosphere, but also proposed as a driver of some of those same processes. This study assesses potential connections between energetic ions observed in the cusp and geomagnetic storm and substorm activity. These connections may suggest sources of cusp energetic particles (CEPs), or imply effects of these particles on magnetospheric dynamics. We identify CEPs from six years of cusp crossings by the Polar satellite, relating them to storm and substorm onsets. CEPs showed no significant dependence on storms but did show a weak, statistically significant, increase after substorm onsets. CEPs had no significant association with subsequent storm or substorm onsets. We conclude that substorm acceleration may contribute to CEPs but CEPs are unlikely to contribute to global magnetospheric dynamics.

How Coherent are Flux Variations in the Outer Van Allen Radiation Belt?

2020 ◽  
Author(s):  
Samuel Walton ◽  
Colin Forsyth ◽  
Iain Jonathan Rae ◽  
Clare Watt ◽  
Richard Horne ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Radiation Belt ◽  
Geomagnetic Storms ◽  
Outer Boundary ◽  
Radial Distance ◽  
Radiation Belts ◽  
Outer Radiation Belt ◽  
Electron Population ◽  
Storms And Substorms ◽  
Using Data

<p>The electron population inside Earth’s outer radiation belt is highly variable and typically linked to geomagnetic activity such as storms and substorms. These variations can differ with radial distance, such that the fluxes at the outer boundary are different from those in the heart of the belt. Using data from the Proton Electron Telescope (PET) on board NASA’s Solar Anomalous Magnetospheric Particle Explorer (SAMPEX), we have examined the correlation between electron fluxes at all L's within the radiation belts for a range of geomagnetic conditions, as well as longer-term averages. Our analysis shows that fluxes at L≈2-4 and L≈4-10 are well correlated within these regions, with coefficients in excess of 80%, however, the correlation between these two regions is low. These correlations vary between storm-times and quiet-times. We examine whether, and to what extent this correlation is related to the level of enhancement of the outer radiation belt during geomagnetic storms, and whether the plasmapause plays any role defining the different regions of correlated flux.</p>

Statistical Study of Loss of GPS Signals Caused by Severe and Great Geomagnetic Storms

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
Shixuan Zhang ◽  
Liming He ◽  
Lixin Wu
Keyword(s):  
Statistical Study ◽  
Geomagnetic Storms
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