Dynamics of large-scale solar-wind streams obtained by the double superposed epoch analysis. 2. CIR.vs.Sheath and MC.vs.Ejecta comparisons

TL;DR

This study compares large-scale solar-wind streams, specifically CIRs, Sheaths, MCs, and Ejecta, using double superposed epoch analysis to understand their physical mechanisms and differences in interplanetary space.

Contribution

It provides detailed comparative analysis of compression regions and ICMEs, proposing a unified physical mechanism and explaining observed parameter differences based on geometry and measurement location.

Findings

All types of compression regions likely share the same physical formation mechanism.

Differences between MC and Ejecta are influenced by the satellite’s position relative to the ICME nose.

Sheath regions significantly impact magnetospheric activity and solar magnetic flux estimates.

Abstract

This work is a continuation of our previous paper [Yermolaevetal2015] which describes the average temporal profiles of interplanetary plasma and field parameters in large-scale solar-wind (SW) streams: CIR, ICME (both MC and Ejecta) and Sheath as well as the interplanetary shock (IS). Like in the previous work we use data of OMNI database, our catalog of large-scale solar-wind phenomena during 1976--2000 [Yermolaevetal2009] and the double superposed epoch analysis (DSEA) method [Yermolaevetal2010]: re-scaling the duration of interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide. We present new detailed results of comparison of two pair phenomena: (1) both types of compression regions (CIR.vs.Sheath) and (2) both types of ICMEs (MC.vs.Ejecta). Obtained data allows us to suggest that the formation of all types of compression regions has the same physical mechanism irrespective of piston (High-Speed Stream (HSS) or ICME) type and differences are connected with geometry (angle between speed gradient in front of piston and satellite trajectory) and full jumps of speed in edges of compression regions. One of consequences of this hypothesis is the conclusion that one of the reasons of observed distinctions of parameters in MC and Ejecta can be fact that at measurements of Ejecta the satellite passes further from the nose area of ICME, than at measurements of MC. We also discuss the impact of Sheath in magnetospheric activity and its contribution in estimation of Sun's open magnetic flux.