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Volume 358 - 36th International Cosmic Ray Conference (ICRC2019) - SH - Solar & Heliospheric
Ratios of SEP/Suprathermal Intensities and Associated CME Speeds
S. Kahler,* A. Ling
*corresponding author
Full text: pdf
Pre-published on: 2019 July 22
Published on:
Abstract
Recently [1] have found correlations between peak intensities Ip of E > 10 MeV SEP events and suprathermal H and He ion intensities observed in situ at 1 AU around the onsets of SEP events. The correlations depend on the solar source longitudes of the driver CMEs and the kind of solar wind (SW) (transient or normal) at the SEP event onset. How the 1 AU suprathermals are related to the solar coronal seed population of SEPs is not known. In a previous study [2] with a similar result, the ratio R of 20-MeV Ip to the 2-MeV H suprathermal backgrounds were plotted against CME speeds Vcme. In contrast to the usual strong correlations between Ip and Vcme, [2] found the dependence of R on Vcme to be very weak, suggesting that the primary factor determining Ip of SEP events may be the source seed population, rather than Vcme. We extend that work [1,2] by plotting both R and log Ip against log Vcme for various types of SW and different source longitudes to look for the dependences of R on Vcme. We confirm the lower correlations found for R and Vcme, but Vcme retains its role as an independent factor in SEP production. The better R correlation using 1.28-2.56 MeV H suggests a more significant role for lower energy 0.16-0.32 MeV H as shock seed particles. Conclusions of variations of R correlations among different SW types and solar longitudes are limited by the statistics of the SEP events.
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