Energy transfer during intense geomagnetic storms driven by interplanetary coronal mass ejections and their sheath regions

Abstract

[1] The interaction of the solar wind and Earth's magnetosphere is complex, and the phenomenology of the interaction is very different for interplanetary coronal mass ejections (ICMEs) compared to their sheath regions. In this paper, a total of 71 intense (Dst ≤ −100 nT) geomagnetic storm events in 1996-2006, of which 51 are driven by ICMEs and 20 by sheath regions, are examined to demonstrate similarities and differences in the energy transfer. Using superposed epoch analysis, the evolution of solar wind energy input and dissipation is investigated. The solar wind-magnetosphere coupling functions and geomagnetic indices show a more gradual increase and recovery during the ICME-driven storms than they do during the sheath-driven storms. However, the sheath-driven storms have larger peak values. In general, solar wind energy input (the epsilon parameter) and dissipation show similar trends as the coupling functions. The trends of ion precipitation and the ratio of ion precipitation to the total (ion and electron) are quite different for both classes of events. There are more precipitating ions during the peak of sheath-driven storms. However, a quantitative assessment of the relative importance of the different energy dissipation branches shows that the means of input energy and auroral precipitation are significantly different for both classes of events, whereas Joule heating, ring current, and total output energy display no distinguishable differences. The means of electron precipitation are significantly different for both classes of events. However, ion precipitation exhibits no distinguishable differences. The energy efficiency bears no distinguishable difference between these two classes of events. Ionospheric processes account for the vast majority of the energy, with the ring current only being 12%-14% of the total. Moreover, the energy partitioning for both classes of events is similar.Citation: Guo, J., X. Feng, B. A. Emery, J. Zhang, C. Xiang, F. Shen, and W. Song (2011), Energy transfer during intense geomagnetic storms driven by interplanetary coronal mass ejections and their sheath regions,

Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

“…The total input and dissipation energies, e.g., solar wind kinetic energy (E sw ), magnetospheric input energy (Eε*), Joule dissipation energy (E J ), auroral precipitation energy (E A ), and ring current energy (E R ), are calculated by timeintegrating the power terms: U sw , ε*, U J , U A , and U R , respectively. It may be mentioned that the above-described methodology of estimation of magnetospheric/ionospheric energy budget has been previously used during geomagnetic storms, substorms, and HILDCAAs with good results (e.g., Turner et al 2006Turner et al , 2009Guo et al 2011Guo et al , 2012Hajra et al 2014b).…”

“…In the above expression, τ is the average ring current decay time. This is taken as~8 h for the present study (Yokoyama and Kamide 1997;Guo et al 2011). The total input and dissipation energies, e.g., solar wind kinetic energy (E sw ), magnetospheric input energy (Eε*), Joule dissipation energy (E J ), auroral precipitation energy (E A ), and ring current energy (E R ), are calculated by timeintegrating the power terms: U sw , ε*, U J , U A , and U R , respectively.…”

Does the duration of the magnetic storm recovery phase depend on the storm development rate in its main phase?

“…As has been shown by numerous papers, the dynamics of the magnetosphere during the development of magnetic storms significantly depends on the type of interplanetary driver (see, e.g., [Huttunen et al, 2002[Huttunen et al, , 2006Borovsky and Denton, 2006;Pulkkinen et al, 2007;Yermolaev et al, 2010Yermolaev et al, , 2012aGuo et al, 2011;Liemohn and Katus, 2012;Nikolaeva et al, 2013;Cramer et al, 2013] and references therein). These types of drivers are following: body of interplanetary CME (ICME) including magnetic cloud (MC) and Ejecta, and compression regions before high-speed solar wind stream (corotating interplanetary region -CIR) and before ICME (Sheath) (see, e.g., [Gosling, 1993;Gonzalez et al, 1999;Yermolaev et al, 2005]).…”

Magnetic-reconnection exhausts in the sheath of magnetic clouds

“…The region of compressed solar wind bounded by the leading shock front and the leading edge of the MC-front is referred to as the sheath region. The sheath regions often have high plasma beta, density, proton temperature, and magnetic-field magnitude (e.g., Guo et al 2010Guo et al , 2011. Within a sheath, the dynamic pressure is typically high and fluctuates more than within MCs, and the magnetic-field direction can change many times.…”