Large solar energetic particles and solar radio emissions during Cycle 25. A comparative analysis of trends and characteristics with cycles 23 and 24

Solar energetic particles (SEPs) affect space weather in both the heliosphere and on Earth. The present study investigates the occurrences of large SEP events focusing on their influence on the Earth, as well as their correlation with solar radio bursts (SRBs). The velocity dispersion analysis (VDA) is used to calculate the release times of large SEP events from their launch locations, as well as their apparent path length that connects them to interplanetary magnetic fields lines. According to the study, 122 large SEP events impacted the planet Earth from 1997 to 2024. The comparison of occurrence rates with previous solar cycles (SCs) suggests that SC 25 will peak with greater solar activity than the cycle 24 in terms of large SEP occurrences since large SEP events correlate well with the pattern of the sunspot cycle progression. In general, a few (35 out of 122) large SEP events are typically released from the Sun at times that coincide with the peak of associated solar flares and the onsets of corresponding SRBs indicating no delay while the rest have delayed in the release. The projected apparent lengths ( L ) range from 1.0 to 3.0 AU, with L exceeding 1.5 AU due to particle scattering and launch site pitch angles. The majority (115/122) of SEP occurrences are accelerated by shock waves from solar flares, CMEs, and fast plasma flow in the magnetic reconnection regions. Relevant SRBs for space weather study as they precede large SEP events diagnose the properties of particle populations propelled by solar flares and CMEs. This study finds that 90% of the large SEP events are preceded by solar radio emissions of type II, III and IV; and WAVES/STEREO revealed ∼ 76 % of SRBs have continuation in IP medium indicating the dynamics of associated shocks and electron beams traveling along open and quasi-open magnetic field lines. Thus, SRB monitoring continues to be a valuable tool for studying space weather and understanding physical phenomena in the solar corona and IP medium, such as particle populations that cause large SEP occurrences.