Analysis of supersubstorm events with reference to polar cap potential and polar cap index

Abstract

The coupling process between solar wind-magnetosphere-ionosphere is an important physical 14 mechanism for the delineating concept of the magnetosphere-ionosphere system. In this work, we have studied the polar cap potential (PCV) and merging electric field (E m ) during three different supersubstorm (SSS) events. We have also studied the roles of polar cap index and auroral electrojet (AE) indices to observe polar cap activity during SSSs. To substantiate results, wavelet transform and cross-correlation techniques are used. We checked the cross correlation of PCV with AE, SYM-H, B z , X, Y, and E y individually. Positive good correlation of PCV with AE and SYM-H is obtained. Observing and obtaining these results, PCV shows the significant effects during geomagnetic activity (SSSs) generated by geoeffective solar wind parameters.

Study of field‐aligned current (FAC), interplanetary electric field component (Ey), interplanetary magnetic field component (Bz), and northward (x) and eastward (y) components of geomagnetic field during supersubstorm

“…Stasiewicz and Potemra [] studied satellite observation and revealed that the magnetospheric FACs show highly complex and variable structures, where current density may vary from a few to several hundred μAm −2 . Adhikari et al [] studied supersubstorm events (on 21 November 2001, 20 January 2005, and 24 August 2005) and found that maximum polar cap potential (PCV) is ~1700 keV with merging electric field ( E m ) ~40 mVm. They found singularity and discontinuity on PCV for SSS events.…”

Ionospheric Effect of Non-Storm Hildcaa (High Intensity Long Duration Continuous Auroral Activity)

“…In order to analyze the local disturbances in the signal, we took Daubechies wavelet coefficients (Gonzalez et al, 1994, Kalausner et al, 2014. The advantage of this method is it can detect the first order disturbances along with its derivatives (Adhikari & Chapagain, 2016). DWT is not only used to find the change in signal but also to detectthe singularities present in signals.…”

“…In this transformation a continuous signal is expressed into wavelets (Grassmann & Morlet, 1983;Adhikari & Chapagain, 2016). The CWT coefficientisis defined as W (a, b) = ʃ f(t) ((t -b)/a) dt; Where represents the complex conjugate of and the parameters a and b are scaling and shifting factors respectively and W (a, b) gives the values of the coefficients.…”

“…Different solar activities change the current system in entire magnetosphere and ionosphere which causes variation in the Earth's magnetic field called geomagnetic disturbance (Guarnieri et al, 2006). The magnetic reconnection between southward interplanetary magnetic field (IMF) and Earth's dayside magnetic field is the key reason for geomagnetic disturbances, which give rise to an electrodynamics coupling between the solar plasma and the magnetosphere (Dungey, 1961;Gonzalez et al, 1994;Adhikari & Chapagain, 2016;Adhikari et al, 2017). The solar sources of the geomagnetic disturbances are known to have various interplanetary manifestations like coronal mass ejection (ICMEs), magnetic clouds, co-rotating interaction region (CIR) and other interplanetary structures like interplanetary shocks (IPS), heliospheric current sheet (HCS) and sector boundary (SB) (Wei et al, 1994;Gonzalez et al, 1999;Klein & Burlaga, 1982).…”

“…HILDCAA (High Intensity Long Duraion Continuous AE activity) is defined as prolongation in duration of high intensity and continuous auroral activities. (Tsurutani & Gonzalez, 1987;Tsurutani et al, 2004;Guarnieri et al, 2006;Hajra et al, 2013;Hajra et al, 2014a;Hajra et al, 2014b;Adhikari & Chapagain, 2016). The auroral activity can be measured by the AE (auroral electrojet) index, which monitors the horizontal component of disturbed magnetic field in the auroral zone (Rostoker, 1972).…”