Comparative analysis of the proton generation efficiency during 17 March 2003 and 11 April 2004 solar flares

Abstract

We present the comparative analysis of the solar energetic particle (SEP) event properties and the indicators of acceleration processes in solar flares − the hard X-rays (HXR) and radio emission from microwaves to the meter-range. We focus our study on the two SEP events associated with solar flares with similar characteristics in HXR emission and the close location on solar disk. The proton flux in the SEP event associated with the weaker flare by GOES class in soft X-ray (SXR) (C9.6/SOL2004-Apr-11) was more than an order higher than in the SEP event associated with the more powerful solar flare (X1.5/SOL2003-Mar-17). At the same time, the electron fluxes in both SEP events were comparable. Both flares were followed by CMEs with speed above 1000 km s−1. The analysis of SEP fluxes and flare plasma parameters was done taking into account the magnetic topology of the active region (AR) and its evolution before and during the solar flares. The 3D reconstruction of the potential magnetic field showed the existence of an arcade of high loops covering the active region where the more powerful flare occurred. The flare associated with the proton-rich SEP event occurred in the active region where 3D reconstruction revealed a fan of high loops associated with open magnetic field lines. We suppose that the arcade of high loops could be the factor which prevents an escape of the accelerated particles into the interplanetary space (IPS) while the fan of high loops facilitates the production of the more proton-rich SEP events. Results of the analysis show a necessity to use topology of ARs as a parameter in statistical studies of SEP event origins.