"Corotating Interaction Regions (CIRs)", "Interaction Regions (IRs)" and "Stream Interaction Regions (SIRs)", which term should be used?

Abstract

We discuss the early history of quasiperiodic ~27-day recurrent geomagnetic activity starting with Maunder (1904, 1905), Chree (1913) and Bartels (1932, 1934), and the Bartels term "M-regions". We show the iconic "interaction region (IR)" schematic of Belcher and Davis (1971) and the further development of Smith and Wolfe (1976) and the term "corotating interaction region (CIR)". We quote the Jian et al. (2006) definition of a "stream interaction region (SIR)". We disagree with Jian et al. (2006) on the use of the term (SIR) to indicate "transient and possibly localized stream interactions" with "poor recurrence" (Gosling et al., 2001). We feel that this description is too vague for use in scientific studies. We suggest, instead identifying the specific known interplanetary phenomena: interplanetary coronal mass ejection (ICME) sheaths, ICMEs (loops, magnetic clouds, filaments), CIRs, high-speed streams (HSSs) and slow streams. All of these various interplanetary phenomena have different solar and interplanetary origins and different plasma and magnetic field properties. The different interplanetary phenomena have been shown to have different geomagnetic effectivenesses. In keeping with this theme of naming specific interplanetary phenomenon, we introduce the term "Super CIR (SCIR)", which describes a CIR associated with magnetic reconnection at the edge of a solar coronal hole with an embedded coronal jet. SCIRs are a new form of a "transient event" and can be identified by exceptionally strong internal magnetic fields and bounded by both forward and reverse shocks. The SCIR on 6-7 April 2000 caused an exceptionally strong SYM-H = -319 nT superstorm, a first detected/reported event of its kind.