Cross-polar cap potential difference, auroral electrojet indices, and solar wind parameters

1992 ◽  
Vol 97 (A2) ◽  
pp. 1345 ◽  
Author(s):  
B. -H. Ahn ◽  
Y. Kamide ◽  
H. W. Kroehl ◽  
D. J. Gorney
Keyword(s):  
Solar Wind ◽  
Auroral Electrojet ◽  
Potential Difference ◽  
Polar Cap ◽  
Cross Polar Cap Potential ◽  
Solar Wind Parameters

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>

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.

scholarly journals A new formulation for the ionospheric cross polar cap potential including saturation effects

2005 ◽  
Vol 23 (11) ◽  
pp. 3533-3547 ◽  
Author(s):  
A. J. Ridley
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Mach Number ◽  
Interplanetary Magnetic Field ◽  
Polar Cap ◽  
Pressure Balance ◽  
Simple Modification ◽  
Post Shock ◽  
Cross Polar Cap Potential ◽  
New Formulation

Abstract. It is known that the ionospheric cross polar cap potential (CPCP) saturates when the interplanetary magnetic field (IMF) Bz becomes very large. Few studies have offered physical explanations as to why the polar cap potential saturates. We present 13 events in which the reconnection electric field (REF) goes above 12mV/m at some time. When these events are examined as typically done in previous studies, all of them show some signs of saturation (i.e., over-prediction of the CPCP based on a linear relationship between the IMF and the CPCP). We show that by taking into account the size of the magnetosphere and the fact that the post-shock magnetic field strength is strongly dependent upon the solar wind Mach number, we can better specify the ionospheric CPCP. The CPCP (Φ) can be expressed as Φ=(10-4v2+11.7B(1-e-Ma/3)sin3(θ/2)) {rms/9 (where v is the solar wind velocity, B is the combined Y and Z components of the interplanetary magnetic field, Ma is the solar wind Mach number, θ=acos(Bz/B), and rms is the stand-off distance to the magnetopause, assuming pressure-balance between the solar wind and the magnetosphere). This is a simple modification of the original Boyle et al. (1997) formulation.

scholarly journals Effects of the solar wind electric field and ionospheric conductance on the cross polar cap potential: Results of global MHD modeling

2003 ◽  
Vol 30 (23) ◽  
pp. n/a-n/a ◽  
Author(s):  
V. G. Merkine ◽  
K. Papadopoulos ◽  
G. Milikh ◽  
A. S. Sharma ◽  
X. Shao ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Polar Cap ◽  
Mhd Modeling ◽  
The Cross ◽  
Cross Polar Cap Potential

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.

Sign in / Sign up

Export Citation Format

Share Document