scholarly journals Analysis of the solar wind IMF Bz and auroral electrojet index during supersubstorms

2021 ◽  
Vol 21 (5) ◽  
pp. 1-10
Author(s):  
Drabindra Pandit ◽  
Narayan P. Chapagain ◽  
Binod Adhikari
Keyword(s):  
Solar Wind ◽  
Auroral Electrojet

scholarly journals Cross-correlation and cross-wavelet analyses of the solar wind IMF <i>B</i><sub><i>z</i></sub> and auroral electrojet index AE coupling during HILDCAAs

2018 ◽  
Vol 36 (1) ◽  
pp. 205-211 ◽  
Author(s):  
Adriane Marques de Souza ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan ◽  
Rajkumar Hajra
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Cross Correlation ◽  
Auroral Electrojet ◽  
Long Duration ◽  
Ae Index ◽  
Speed Solar Wind ◽  
Wavelet Analyses ◽  
Cross Wavelet ◽  
High Speed Solar Wind

Abstract. Solar-wind–geomagnetic activity coupling during high-intensity long-duration continuous AE (auroral electrojet) activities (HILDCAAs) is investigated in this work. The 1 min AE index and the interplanetary magnetic field (IMF) Bz component in the geocentric solar magnetospheric (GSM) coordinate system were used in this study. We have considered HILDCAA events occurring between 1995 and 2011. Cross-wavelet and cross-correlation analyses results show that the coupling between the solar wind and the magnetosphere during HILDCAAs occurs mainly in the period ≤ 8 h. These periods are similar to the periods observed in the interplanetary Alfvén waves embedded in the high-speed solar wind streams (HSSs). This result is consistent with the fact that most of the HILDCAA events under present study are related to HSSs. Furthermore, the classical correlation analysis indicates that the correlation between IMF Bz and AE may be classified as moderate (0.4–0.7) and that more than 80 % of the HILDCAAs exhibit a lag of 20–30 min between IMF Bz and AE. This result corroborates with Tsurutani et al. (1990) where the lag was found to be close to 20–25 min. These results enable us to conclude that the main mechanism for solar-wind–magnetosphere coupling during HILDCAAs is the magnetic reconnection between the fluctuating, negative component of IMF Bz and Earth's magnetopause fields at periods lower than 8 h and with a lag of about 20–30 min. Keywords. Magnetospheric physics (solar-wind–magnetosphere interactions)

scholarly journals Comparative study of dynamical critical scaling in the auroral electrojet index versus solar wind fluctuations

2001 ◽  
Vol 28 (19) ◽  
pp. 3809-3812 ◽  
Author(s):  
Vadim M. Uritsky ◽  
Alex J. Klimas ◽  
Dimitris Vassiliadis
Keyword(s):  
Solar Wind ◽  
Comparative Study ◽  
Auroral Electrojet ◽  
Critical Scaling

scholarly journals Forecasting auroral electrojet activity from solar wind input with neural networks

1999 ◽  
Vol 26 (10) ◽  
pp. 1353-1356 ◽  
Author(s):  
R. S. Weigel ◽  
W. Horton ◽  
T. Tajima ◽  
T. Detman
Keyword(s):  
Neural Networks ◽  
Solar Wind ◽  
Auroral Electrojet ◽  
Wind Input

scholarly journals Effects of solar wind density on auroral electrojets and brightness under influence of substorms

2009 ◽  
Vol 27 (1) ◽  
pp. 113-119 ◽  
Author(s):  
J.-H. Shue ◽  
Y. Kamide ◽  
J. W. Gjerloev
Keyword(s):  
Solar Wind ◽  
Auroral Oval ◽  
Auroral Electrojet ◽  
The Other ◽  
Auroral Ionosphere ◽  
Stored Energy ◽  
Solar Wind Density ◽  
The Earth ◽  
Density Enhancement ◽  
Solar Wind Parameters

Abstract. Using the auroral electrojet indices and Polar Ultraviolet Imager auroral images, we examined two fortuitous events during which the solar wind density had clear enhancements while the other solar wind parameters were relatively constant. Two electrojet enhancements were found in each event. The first electrojet enhancement was likely to be related to a substorm in which an auroral bulge appeared at premidnight. The second electrojet enhancement was driven by the density enhancement in the solar wind. The auroral oval became wider in latitude and the auroral distribution became dispersed after the density enhancement arrived at the Earth. The total auroral power integrated over the entire nightside region from 50 to 80° MLAT, however, did not increase significantly in response to the density enhancement. Our interpretation is that the substorm that occurred prior to the solar wind density enhancement had drained out a significant portion of the stored energy in the magnetotail; therefore, less precipitation energy was deposited into the auroral ionosphere by the density enhancement.

scholarly journals Polar Cap Potential and Merging Electric Field during High Intensity Long Duration Continuous Auroral Activity

2016 ◽  
Vol 3 (1) ◽  
pp. 6 ◽  
Author(s):  
Binod Adhikari ◽  
Narayan P. Chapagain
Keyword(s):  
Solar Wind ◽  
Wavelet Transform ◽  
Electric Field ◽  
High Intensity ◽  
Cross Correlation ◽  
Auroral Electrojet ◽  
Polar Cap ◽  
Auroral Activity ◽  
Long Duration ◽  
Solar Wind Parameters

<p>The polar cap potential (PCV) has long been considered as a key parameter for describing the state of the magnetosphere/ionosphere system. The relationship between the solar wind parameters and the PCV is important to understand the coupling process between solar wind-magnetosphere-ionosphere. In this work, we have estimated PCV and merging electric field (Em) during two different high intensity long duration continuous auroral activity (HILDCAA) events. For each event, we examine the solar wind parameters, magnitude of interplanetary magnetic field (IMF), interplanetary electric field (IEF), PCV, Em and geomagnetic indices (i.e., SYM-H, geomagnetic auroral electrojet (AE) index, polar cap index (PCI) and auroral electrojet index lower (AL), respectively). We also study the role of PCI and AL indices to monitor polar cap (PC) activity during HILDCAAs. In order to verify their role, we use wavelet transform and cross-correlation techniques. For the three events studied here, the results obtained from continuous wavelet transform (CWT) and discrete wavelet transform (DWT) are different, however the effect of HILDCAA can be easily identified. We also observe the cross-correlation of PCI and PCV with AL, SYM-H, Bz component of the IMF and Ey component of the IEF individually. Both PCI and PCV show very good correlation with AL and SYM-H indices during the events. Observing these results, it can be suggested that PCI and AL indices play a significant role to monitor geomagnetic activity generated by geoeffective solar wind parameters.</p><p>Journal of Nepal Physical Society Vol.3(1) 2015: 6-17</p>

Local amplification of auroral electrojet as a response to a sharp solar wind pressure pulse

2005 ◽  
Vol 53 (1-3) ◽  
pp. 265-274 ◽  
Author(s):  
V.A. Parkhomov ◽  
M.O. Riazantseva ◽  
G.N. Zastenker
Keyword(s):  
Solar Wind ◽  
Pressure Pulse ◽  
Auroral Electrojet ◽  
Wind Pressure ◽  
Solar Wind Pressure

scholarly journals Rank ordering multifractal analysis of the auroral electrojet index

2011 ◽  
Vol 18 (3) ◽  
pp. 277-285 ◽  
Author(s):  
G. Consolini ◽  
P. De Michelis
Keyword(s):  
Solar Wind ◽  
Multifractal Analysis ◽  
Geomagnetic Storms ◽  
Small Time ◽  
Auroral Electrojet ◽  
Rank Ordering ◽  
Ae Index ◽  
Complex Features ◽  
Scaling Features ◽  
Multifractal Nature

Abstract. In the second half of the 90s interest grew on the complex features of the magnetospheric dynamics in response to solar wind changes. An important series of papers were published on the occurrence of chaos, turbulence and complexity. Among them, particularly interesting was the study of the bursty and fractal/multifractal character of the high latitude energy release during geomagnetic storms, which was evidenced by analyzing the features of the Auroral Electrojet (AE) indices. Recently, the multifractal features of the small time-scale increments of AE-indices have been criticized in favor of a more simple fractal behavior. This is particularly true for the scaling features of the probability density functions (PDFs) of the AE index increments. Here, after a brief review of the nature of the fractal/multifractal features of the magnetospheric response to solar wind changes, we investigate the multifractal nature of the scaling features of the AE index increments PDFs using the Rank Ordering Multifractal Analysis (ROMA) technique. The ROMA results clearly demonstrate the existence of a hierarchy of scaling indices, depending on the increment amplitude, for the data collapsing of PDFs relative to increments at different time scales. Our results confirm the previous results by Consolini et al. (1996) and the more recent results by Rypdal and Rypdal (2010).

scholarly journals On the Saturation (or Not) of Geomagnetic Indices

2021 ◽  
Vol 8 ◽  
Author(s):  
Joseph E. Borovsky
Keyword(s):  
Solar Wind ◽  
Auroral Electrojet ◽  
Polar Cap ◽  
Ulf Wave ◽  
Geomagnetic Indices ◽  
Particle Pressure ◽  
Index Saturation ◽  
Cross Polar Cap Potential ◽  
Current Systems

Most geomagnetic indices are associated with processes internal to the magnetosphere-ionosphere system: convection, magnetosphere-ionosphere current systems, particle pressure, ULF wave activity, etc. The saturation (or not) of various geomagnetic indices under various solar-wind driver functions (a.k.a. coupling functions) is explored by examining plots of the various indices as functions of the various driver functions. In comparing an index with a driver function, “saturation” of the index means that the trend of stronger geomagnetic activity with stronger driving weakens in going from mid-range driving to very strong driving. Issues explored are 1) whether the nature of the index matters (i.e., what the index measures and how the index measures it), 2) the relation of index saturation to cross-polar-cap potential saturation, and 3) the role of the choice of the solar-wind driver function. It is found that different geomagnetic indices exhibit different amounts of saturation. For example the SuperMAG auroral-electrojet indices SME, SML, and SMU saturate much less than do the auroral-electrojet indices AE, AL, and AU. Additionally it is found that different driver functions cause an index to show different degrees of saturation. Dividing a solar-wind driver function by the theoretical cross-polar-cap-potential correction (1+Q) often compensates for the saturation of an index, even though that index is associated with internal magnetospheric processes whereas Q is derived for solar-wind processes. There are composite geomagnetic indices E(1) that show no saturation when matched to their composite solar-wind driver functions S(1). When applied to other geomagnetic indices, the composite S(1) driver functions tend to compensate for index saturation at strong driving, but they also tend to introduce a nonlinearity at weak driving.

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