Recovery phase of magnetic storms induced by different interplanetary drivers

Abstract

Statistical analysis of Dstbehavior 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 (Dstmin ≤ −100 nT) magnetic storms are well approximated by hyperbolic functions Dst(t) = a/(1 + t/τh) with constant τh times for each types of drivers while for moderate (−100 < Dstmin ≤ −50 nT) storms Dst profile can not be approximated by hyperbolic function with constant τh times because hyperbolic τh times increase with increasing time of recovery phase. Dependence of τh times on types of interplanetary drivers is the same as indicated above. Relation between duration and value Dstmin for storms induced by MC and Sheath has 2 parts: module of Dstmin 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.