Coronal mass ejections as a new indicator of the active Sun

TL;DR

This paper proposes coronal mass ejections (CMEs) as a superior indicator of solar activity, linking them to magnetic regions and sunspot cycles, and demonstrating their correlation with geomagnetic disturbances.

Contribution

It introduces CMEs as a new, more comprehensive indicator of solar activity, connecting magnetic regions and sunspot cycles, and analyzing their geospace impacts.

Findings

CMEs are better indicators of solar activity than sunspots.

CME speeds correlate with geomagnetic activity indices.

North-south reversal asymmetry has a 3-5 solar cycle quasi-periodicity.

Abstract

Coronal mass ejections (CMEs) have become one of the key indicators of solar activity, especially in terms of the consequences of the transient events in the heliosphere. Although CMEs are closely related to the sunspot number (SSN), they are also related to other closed magnetic regions on the Sun such as quiescent filament regions. This makes CMEs a better indicator of solar activity. While sunspots mainly represent the toroidal component of solar magnetism, quiescent filaments (and hence CMEs associated with them) connect the toroidal and poloidal components via the rush-to-the-pole (RTTP) phenomenon. Taking the end of RTTP in each hemisphere as an indicator of solar polarity reversal, it is shown that the north-south reversal asymmetry has a quasi-periodicity of 3-5 solar cycles. Focusing on the geospace consequences of CMEs, it is shown that the maximum CME speeds averaged over Carrington rotation period show good correlation with geomagnetic activity indices such as Dst and aa.