Geoeffectiveness and efficiency of CIR, Sheath and ICME in generation of magnetic storms

TL;DR

This study analyzes how different solar wind streams, including CIRs, Sheath regions, and ICMEs, contribute to magnetic storm generation, highlighting the high geoeffectiveness of magnetic clouds despite their lower occurrence.

Contribution

It provides a comparative analysis of the roles and efficiencies of various solar wind types in generating magnetic storms using extensive interplanetary data from 1976-2000.

Findings

Magnetic clouds have higher geoeffectiveness despite lower occurrence.

CIRs and Sheath regions are more frequent and efficient in storm generation.

Magnetic clouds often contain strong southward IMF Bz, leading to intense storms.

Abstract

We investigate relative role of various types of solar wind streams in generation of magnetic storms. On the basis of the OMNI data of interplanetary measurements for the period of 1976-2000 we analyze 798 geomagnetic storms with Dst < -50 nT and their interplanetary sources: corotating interaction regions (CIR), interplanetary CME (ICME) including magnetic clouds (MC) and Ejecta and compression regions Sheath before both types of ICME. For various types of solar wind we study following relative characteristics: occurrence rate; mass, momentum, energy and magnetic fluxes; probability of generation of magnetic storm (geoeffectiveness) and efficiency of process of this generation. Obtained results show that despite magnetic clouds have lower occurrence rate and lower efficiency than CIR and Sheath they play an essential role in generation of magnetic storms due to higher geoeffectiveness of storm generation (i.e higher probability to contain large and long-term southward IMF Bz component).