Recovery phase of magnetic storms induced by different interplanetary drivers

Abstract

[1] Statistical analysis of Dst behavior during recovery phase of magnetic storms induced by different types of interplanetary drivers is made on the basis of OMNI data in period 1976-2000. We study storms induced by ICMEs (including magnetic clouds (MC) and Ejecta) and both types of compressed regions: corotating interaction regions (CIR) and Sheaths. The shortest, moderate and longest durations of recovery phase are observed in ICME-, CIR-, and Sheath-induced storms, respectively. Recovery phases of strong (Dst min ≤ À100 nT) magnetic storms are well approximated by hyperbolic functions Dst(t) = a/(1 + t/t h ) with constant t h times for each types of drivers while for moderate (À100 < Dst min ≤ À50 nT) storms Dst profile can not be approximated by hyperbolic function with constant t h times because hyperbolic t h times increase with increasing time of recovery phase. Dependence of t h times on types of interplanetary drivers is the same as indicated above. Relation between duration and value Dst min for storms induced by MC and Sheath has 2 parts: module of Dst min and duration correlate at small durations while they anticorrelate at large durations. Obtained results show that recovery phase Dst variations depend on type of interplanetary drivers inducing magnetic storms.

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

“…This paper is a continuation of our previous paper [Yermolaev et al, 2012b], and we use the same databases (OMNI data of interplanetary plasma and magnetic field parameters (see http://omniweb.gsfc.nasa.gov) [King and Papitashvili, 2004] and measurements of Dst index (see http://wdc.kugi.kyoto-u.ac.jp/index.html for the period of 1976-2000)) and the same method of classification of large-scale solar wind streams (see our catalog of large-scale interplanetary events for 1976-2000 on the web site ftp://www.iki.rssi.ru/pub/ omni [Yermolaev et al, 2009]). We analyze separately 798 moderate (with −100nT < Dst min ≤ −50 nT) and strong (Dst min ≤ −100 nT) magnetic storms.…”

“…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.…”

“…All Rights Reserved. [Yermolaev et al, 2012b] duration of the recovery phase and |Dst min | correlate for short storm durations, and they have an inverse correlation for long storm durations, while for storms generated by CIR and Ejecta, the durations of the recovery phase depend slightly on Dst min .…”

“…In our recent paper [Yermolaev et al, 2012b], we showed that the recovery phase Dst variations depend on the type of interplanetary driver inducing the magnetic storms (i.e., the magnetosphere remembers the type of inducing driver during the recovery phase) and the durations of the recovery phase for storms induced by a CIR or a Sheath are longer than for storms induced by MC or Ejecta.…”

“…The recovery phase of magnetic storms and processes responsible for a decay of ring current have been the subject of numerous papers [see, e.g., Daglis et al, 1999;Keika et al, 2006;Xu and Du, 2010;O'Brien and McPherron, 2000;Feldstein et al, 2000;Monreal MacMahon and Llop-Romero, 2008;Yermolaev et al, 2012b;Cid et al, 2013, and references therein]. In our recent paper [Yermolaev et al, 2012b], we showed that the recovery phase Dst variations depend on the type of interplanetary driver inducing the magnetic storms (i.e., the magnetosphere remembers the type of inducing driver during the recovery phase) and the durations of the recovery phase for storms induced by a CIR or a Sheath are longer than for storms induced by MC or Ejecta.…”