On the Relation between Flare and CME during GLE-SEP and Non-GLE-SEP Events

Abstract

Association of solar flares and coronal mass ejections (CMEs) with ground-level enhancement (GLE) is a recognized fact, but questions arise when a similar association is observed for non-GLEs. In this respect, we carry out a detailed study of the relation between flare fluences (ϕ J m^-2) and CME speeds (V _cme km s^-1) during some selected GLEs and non-GLEs. As we found, most of the data points of ϕ (J m^-2) and V _cme (km s^-1) of GLEs follow a near-linear trend, with the ϕ (J m^-2) increasing as the V _cme (km s^-1) increases, resulting in a strong positive correlation (r ≥ 0.82), while the correlation (r ≤ 0.47) remains weak for non-GLEs. For any exceptional GLE, the ϕ (J m^-2) and V _cme (km s^-1) that do not maintain a near-linear trend over the whole flare phase do maintain at least a minimum rational proportionality over the flare rise phase, whereas this characteristic was not generally observed for non-GLEs. Although the ϕ (J m^-2) and V _cme (km s^-1) of some non-GLEs show a trend similar to those of GLEs, they indeed originated over the flare impulsive phases concomitant with coronal shock manifested in m type II bursts, while GLEs originated over the flare initial phase before the m type II. Flare peak fluences (ϕ _pk J m^-2) and V _cme (km s^-1) maintain weak correlation for both GLEs and non-GLEs, likely because the CME main acceleration ceases around the flare peak. However, though the ϕ _pk (J m^-2) governs the flare total fluence, it does not blur the correlation between the fluence over the flare rise phase (ϕ _r J m^-2) and V _cme (km s^-1), indicating that the flare peak/strength does not control the GLE occurrence.