Statistical relationship between solar wind conditions and geomagnetic storms in 1998–2008

Abstract. The NARMAX OLS-ERR methodology is applied to identify a mathematical model for the dynamics of the Dst index. The NARMAX OLS-ERR algorithm, which is widely used in the field of system identification, is able to identify a mathematical model for a wide class of nonlinear systems using input and output data. Solar wind-magnetosphere coupling functions, derived from analytical or data based methods, are employed as the inputs to such models and the outputs are geomagnetic indices. The newly deduced coupling function, p1/2V4/3BTsin6(θ/2), has been implemented as an input to model the Dst dynamics. It was shown that the identified model has a very good forecasting ability, especially with the geomagnetic storms.

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A neural network-based mid-term prognosis of geomagnetic storms that uses pre-storm effects related to current sheets and magnetic islands

10.5194/egusphere-egu21-8087 ◽

2021 ◽

Author(s):

Mikhail Fridman

Keyword(s):

Solar Wind ◽

Solar Minimum ◽

High Speed ◽

Geomagnetic Storms ◽

Magnetic Islands ◽

Solar Wind Density ◽

Short Term ◽

Storm Effects ◽

Term Forecast ◽

Advance Time

<p>Mid-term prognoses of geomagnetic storms require an improvement since the&#1091; are known to have rather low accuracy which does not exceed 40% in solar minimum. We claim that the problem lies in the approach. Current mid-term forecasts are typically built using the same paradigm as short-term ones and suggest an analysis of the solar wind conditions typical for geomagnetic storms. According to this approach, there is a 20-60 minute delay between the arrival of a geoeffective flow/stream to L1 and the arrival of the signal from the spacecraft to Earth, which gives a necessary advance time for a short-term prognosis. For the mid-term forecast with an advance time from 3 hours to 3 days, this is not enough. Therefore, we have suggested finding precursors of geomagnetic storms observed in the solar wind. Such precursors are variations in the solar wind density and the interplanetary magnetic field in the ULF range associated with crossings of magnetic cavities in front of the arriving geoeffective high-speed streams and flows (Khabarova et al., 2015, 2016, 2018; Adhikari et al., 2019). Despite some preliminary studies have shown that this might be a perspective way to create a mid-term prognosis (Khabarova 2007; Khabarova & Yermolaev, 2007), the problem of automatization of the prognosis remained unsolved.</p>

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The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

Annales Geophysicae ◽

10.5194/angeo-34-45-2016 ◽

2016 ◽

Vol 34 (1) ◽

pp. 45-53 ◽

Cited By ~ 2

Author(s):

W. Chu ◽

G. Qin

Keyword(s):

Solar Wind ◽

Cosmic Rays ◽

Strong Correlation ◽

Geomagnetic Storms ◽

Dynamic Pressure ◽

Threshold Value ◽

High Latitudes ◽

Dst Index ◽

Ae Index ◽

Geomagnetic Cutoff

Abstract. Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

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Total electron content responses to HILDCAAs and geomagnetic storms over South America

Annales Geophysicae ◽

10.5194/angeo-35-1309-2017 ◽

2017 ◽

Vol 35 (6) ◽

pp. 1309-1326 ◽

Cited By ~ 5

Author(s):

Patricia Mara de Siqueira Negreti ◽

Eurico Rodrigues de Paula ◽

Claudia Maria Nicoli Candido

Keyword(s):

Solar Wind ◽

South America ◽

Total Electron Content ◽

Geomagnetic Storm ◽

Electric Fields ◽

Geomagnetic Storms ◽

Time Variability ◽

Electron Content ◽

Quiet Time ◽

Total Electron

Abstract. Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ∼  25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and considering the events studied here, this was the most important source of ionospheric responses. Furthermore, the most important source of TEC changes were the long-lasting PPEFs observed on August 2013, during the HILDCAA event. The importance of this study relies on the peculiarity of the region analyzed characterized by high declination angle and ionospheric gradients which are responsible for creating a complex response during disturbed periods.

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Effect of solar wind variation on low-energy O+populations in the magnetosphere during geomagnetic storms: FAST observations

Journal of Geophysical Research Atmospheres ◽

10.1029/2007ja012681 ◽

2008 ◽

Vol 113 (A4) ◽

pp. n/a-n/a ◽

Cited By ~ 10

Author(s):

Y. Yao ◽

K. Seki ◽

Y. Miyoshi ◽

J. P. McFadden ◽

E. J. Lund ◽

...

Keyword(s):

Solar Wind ◽

Geomagnetic Storms ◽

Low Energy

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A UNIFYING THEORY OF HIGH-LATITUDE GEOPHYSICAL PHENOMENA AND GEOMAGNETIC STORMS

Canadian Journal of Physics ◽

10.1139/p61-172 ◽

1961 ◽

Vol 39 (10) ◽

pp. 1433-1464 ◽

Cited By ~ 1076

Author(s):

W. I. Axford ◽

C. O. Hines

Keyword(s):

Solar Wind ◽

Steady State ◽

High Latitude ◽

Geomagnetic Storms ◽

High Latitudes ◽

Full Understanding ◽

Earth’S Magnetosphere ◽

Trapped Particles ◽

Outer Portion ◽

Earth's Magnetosphere

This paper is concerned with the occurrence at high latitudes of a large number of geophysical phenomena, including geomagnetic agitation and bay disturbances, aurorae, and various irregular distributions of ionospheric electrons. It shows that these may all be related in a simple way to a single causal agency, namely, a certain convection system in the outer portion of the earth's magnetosphere. The source of this convection is taken to be a viscous-like interaction between the magnetosphere and an assumed solar wind, though other sources of an equivalent nature may also be available. The model is capable of accounting for many aspects of the phenomena concerned, including the morphology of auroral forms and the occurrence of 'spiral' patterns in the loci of maximum intensities of several features. It also bears directly on the steady state of the magnetosphere, and in particular on the production of trapped particles in the outer Van Allen belt. In short, it provides a new basis on which a full understanding of these several phenomena may in time be built.

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Role of the magnetospheric and ionospheric currents in the generation of the equatorial scintillations during geomagnetic storms

Annales Geophysicae ◽

10.5194/angeo-22-3195-2004 ◽

2004 ◽

Vol 22 (9) ◽

pp. 3195-3202 ◽

Cited By ~ 17

Author(s):

L. Z. Biktash

Keyword(s):

Solar Wind ◽

Electric Fields ◽

Ring Current ◽

Geomagnetic Storms ◽

Equatorial Ionosphere ◽

Experimental Investigations ◽

Polar Regions ◽

Ionospheric Currents ◽

Geomagnetic Variations ◽

Activity Effect

Abstract. The equatorial ionosphere parameters, Kp, Dst, AU and AL indices characterized contribution of different magnetospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the geomagnetic activity effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict near 70% of scintillations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of electron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind - magnetosphere - ionosphere during magnetic storms have progressed greatly. According to present view, the intensity of the electric fields and currents at the polar regions, as well as the magnetospheric ring current intensity, are strongly dependent on the variations of the interplanetary magnetic field. The magnetospheric ring current cannot directly penetrate the equatorial ionosphere and because of this difficulties emerge in explaining its relation to scintillation activity. On the other hand, the equatorial scintillations can be observed in the absence of the magnetospheric ring current. It is shown that in addition to Aarons' criteria for the prediction of the ionospheric scintillations, models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere currents and the solar wind.

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White-light solar corona structure observed by naked eye and processed images

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1377 ◽

2020 ◽

Vol 495 (2) ◽

pp. 2170-2178 ◽

Cited By ~ 1

Author(s):

Vojtech Rušin ◽

Paul Prikryl ◽

Emil A Prikryl

Keyword(s):

Solar Wind ◽

White Light ◽

High Speed ◽

Geomagnetic Storms ◽

Interplanetary Space ◽

Coronal Holes ◽

Human Vision ◽

Naked Eye ◽

Wide Range ◽

White Light Corona

ABSTRACT Light and dark adaptation and luminance contrast enhancement are well-known characteristics of human vision that allow us to observe a wide range of light intensity not fully captured in standard camera images. The naked-eye observations of total eclipses, some recorded with spectacular detail in artists’ paintings, reveal structure that is consistent with images obtained by telescopes equipped with recording media. The actual shape of the corona during a total eclipse depends not only on the phase of the solar cycle but, as can be simply demonstrated, also on the day-to-day variability and spatial distribution of coronal intensity that is determined by solar surface magnetic fields, including the locations of coronal holes that are the sources of high-speed solar wind causing geomagnetic storms. The latter were very similar for the eclipses in 1932, 1994, and 2017, which is the main reason why the naked-eye observations, as well as the processed images (1994 and 2017), of the white-light corona displayed very similar shapes. White-light corona image processing is a useful technique to enhance the contrast to observe fine-scale structure that is consistent with the physics of the solar atmosphere shaped by the magnetic field drawn out into the interplanetary space by solar wind.

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