- The paper correlates SEP events with solar flares and CMEs across Solar Cycles 21-24, emphasizing western hemisphere origins and magnetic connectivity.
- The paper examines CME properties, revealing an average speed of 1238 km/s and a high incidence of halo CMEs crucial for SEP production.
- The paper analyzes the weak correlation between X-ray flare intensity and SEP magnitude, suggesting shock and magnetic reconnection processes jointly drive SEP events.
An Expert Analysis of "Characteristics of SEPs during Solar Cycle 21-24"
The research paper titled "Characteristics of SEPs during Solar Cycle 21-24" represents a comprehensive study of solar energetic particle (SEP) events across solar cycles 21 to 24, encompassing the period from 1976 to 2017. The authors Raj Kumar, Ramesh Chandra, Bimal Pande, and Seema Pande aim to elucidate the relationship between SEP events and solar flares, as well as the characteristics of coronal mass ejections (CMEs) associated with these particles. The study predominantly utilizes data from monitoring instruments onboard the Solar and Heliospheric Observatory (SOHO) satellite.
Summary of Findings
The research characterizes SEP events with an intensity of ≥ 10 pfu in the >10 MeV energy channels, linking them to solar flares during the specified solar cycles. Key findings of the study include:
- Source Distribution: A significant asymmetry is observed in the originating hemispheres of SEPs, with approximately 69% of the events emanating from the western solar hemisphere, ostensibly due to favorable magnetic connectivity facilitating SEP propagation towards Earth.
- CME Characteristics: Analysis marks the average CME speed at roughly 1238 km/s, with widths averaging 253 degrees. A substantial 58% of these events were associated with halo CMEs, indicative of their wide spatial distribution and potential for strong SEP production.
- Solar Flares: A notable portion of SEPs is tied to GOES M and X-class flares, with correlation analysis suggesting a weak association between SEP intensity and X-ray flux from these flares. The study posits that both shock wave-driven and magnetic reconnection mechanisms contribute to SEP generation during solar eruptions.
Statistical Analysis and Correlation
The researchers provide a robust statistical analysis of SEP events, examining correlations between SEP intensity and various flare and CME parameters. While there is a moderate correlation between CME speed and SEP intensity, the relationship between solar flare intensity and SEP events is less pronounced. The correlation coefficients vary with longitudinal location on the solar surface, underscoring the complexity in forecast modeling.
Theoretical and Practical Implications
The study's insights into the solar origin of SEPs bear significant implications for space weather forecasting and hazard mitigation. Understanding the correlation between SEPs and solar activity aids in improving prediction models crucial for satellite operations and astronaut safety. The results highlight the need for integrating multiple physical parameters, including the magnetic topology of active regions, to fully understand SEP dynamics.
Prospects for Future Research
Despite significant contributions, the paper underscores existing knowledge gaps, particularly in precisely correlating SEP events with their solar origins. Future research could benefit from observations by multi-point spacecraft missions, such as the Parker Solar Probe and Solar Orbiter, to enhance the understanding of solar wind and SEP propagation.
The data presented, spanning multiple solar cycles, offers a substantial basis for ongoing research, aiming to refine the physical models related to SEP production and propagation. Such developments hold promise for advancing our capacity to predict and mitigate the adverse effects of solar activity on terrestrial and satellite systems.
