Solar Energetic Particle-Associated Coronal Mass Ejections Observed by the Mauna Loa Solar Observatory Mk3 and Mk4 Coronameters

TL;DR

This study analyzes low-corona CME observations from MLSO to understand their link with solar energetic proton events, aiming to identify early warning signatures for SEP events, despite challenges in measuring CME dynamics accurately.

Contribution

It provides the first comprehensive analysis of CME motions in the low corona associated with SEP events using MLSO data combined with space-based observations, highlighting measurement challenges.

Findings

SEP-associated CMEs are generally faster and wider.

Measurement techniques yield inconsistent CME dynamics estimates.

Early CME signatures for SEP warning are difficult to reliably identify.

Abstract

We report on the first comprehensive study of the coronal mass ejections (CMEs) associated with $\sim$25 MeV solar energetic proton (SEP) events in 1980-2013 observed in the low/inner corona by the Mauna Loa Solar Observatory (MLSO) Mk3 and Mk4 coronameters. Where possible, these observations are combined with spacebased observations from the Solar Maximum Mission C/P, P78-1 SOLWIND or SOHO/LASCO coronagraphs. The aim of the study is to understand directly-measured (rather than inferred from proxies) CME motions in the low to middle corona and their association with SEP acceleration, and hence attempt to identify early signatures that are characteristic of SEP acceleration in ground-based CME observations that may be used to warn of impending SEP events. Although we find that SEP events are associated with CMEs that are on average faster and wider than typical CMEs observed by MLSO, a major challenge turns out to be determining reliable estimates of the CME dynamics in the low corona from the 3-minute cadence Mk3/4 observations since different analysis techniques can produce inconsistent results. This complicates the assessment of what early information on a possible SEP event is available from these low coronal observations