Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

Abstract

Abstract.A comparison of specific interplanetary conditions for 798 magnetic storms with Dst < −50 nT during 1976-2000 was made on the basis of the OMNI archive data. We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including both magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and minimum of Dst index) and makes a re-scaling of the main phase of the storm in a such way that all storms have equal durations of the main phase in the new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate that (1) in accordance with "output/input" criteria the highest efficiency in generation of magnetic storms is observed for Sheath and the lowest one for MC, and (2) there are significant differences in the properties of MC and Ejecta and in their efficiencies.

Influence of the interplanetary driver type on the durations of the main and recovery phases of magnetic storms

“…In accordance with our results [Yermolaev et al, 2010;Nikolaeva et al, 2013Nikolaeva et al, , 2014, the intensity of a magnetic storm at its main phase may be approximated by the following formula:…”

“…Because a magnetic storm can begin at any value of Dst index, depending on the previous state of the magnetosphere, the average values < Dst(t 1 ) > (−6 nT for CIR, −12 nT for Sheath, and −17 nT for ICME) [Yermolaev et al, 2010] are close to each other and small relative to the second term of the equation, i.e., this term does not make a noticeable contribution in comparison with the outputs for the various interplanetary drivers. The values < E y > and < ΔT > are close to each other for the different types of drivers (the values < Ey > are 16.24 ± 9.78 for MC, 16.4 ± 13.5 for Sheath, 13.3 ± 10.4 for CIR, and 15.6 ± 11.8 for Ejecta [Nikolaeva et al, 2013], and see < ΔT > in Table 1), while the < C SW > coefficients significantly depend on the type of interplanetary driver: these coefficients are large (−3.2 ± 1.6 and −2.82 ± 1.1) for Sheath and CIR and small (−2.55±0.75 and −2.3±1.0) for MC and Ejecta [Nikolaeva et al, 2013].…”

“…Our analysis showed that during this period, CIR, Sheath, MC, and Ejecta generated 145, 96, 62, and 161 magnetic storms, respectively. The interplanetary sources of the other 334 magnetic storms are indeterminate because of data gaps (indicated here as IND-induced storms) [Yermolaev et al, 2009[Yermolaev et al, , 2010[Yermolaev et al, , 2012a[Yermolaev et al, , 2012b. About 25% of the storms were multistep ones during their main and recovery phases, and these storms were excluded from the analysis.…”

“…For example, Wang et al [2003] found that a southward field component Bz ≤ −3 nT with a duration of Δt ≥ 1 h results in moderate magnetic storms (Dst min ≤ −50 nT) and threshold values of Bz ≤ −6 nT with a duration of Δt ≥ 2 h result in strong magnetic storms (Dst min ≤ −100 nT), and these results differ somewhat from the results of previous papers by Russell et al [1974], Gonzalez and Tsurutani [1987], and Gonzalez et al [1994]. The papers mentioned above analyzed the duration of the southward IMF Bz component which is enough to generate magnetic storms, but the duration of the main phase was studied less intensively and it was shown that the duration of the main phase may be from 2 h to 1 day [see, e.g., Yokoyama and Kamide, 1997;Vieira et al, 2004;Vichare et al, 2005;Gonzalez and Echer, 2005;Yermolaev et al, 2007aYermolaev et al, , 2007bHutchinson et al, 2011;Nikolaeva et al, 2012, and Though it is well known that the dynamics of magnetic storms depends on the type of interplanetary drivers (see, e.g., papers by Borovsky and Denton [2006], Yermolaev et al [2010Yermolaev et al [ , 2012a, Guo et al [2011], Liemohn and Katus [2012], Nikolaeva et al [2013], Cramer et al [2013], and references therein), the majority of previous works have not made a selection by types of solar wind streams which generated the storms. In other works, the selection was either performed only for a limited type of solar wind or for a complex of types.…”

Impact of Solar Wind on the Earth Magnetosphere: Recent Progress in the Modeling of Ring Current and Radiation Belts

“…Many previous studies have addressed the question of solar wind drivers for geomagnetic storms. Most of these were statistical in nature Denton et al, 2006;Turner et al, 2009;Weigel, 2010;Yermolaev et al, 2010;Zhang, Richardson, Webb, Gopalswamy, Huttunen, Kasper, Nitta, Poomvises, Thompson, Wu, Yashiro & Zhukov, 2007). They focused upon the effectiveness of different types of solar wind structures in producing geomagnetic disturbances (e.g., a combinations of global activity indices and/or various coupling functions) and different types of storms.…”