Fig. 2.
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Occurrence of SEP events is related to the solar activity cycle. Panel a shows the entire SEPEM dataset used in this study, namely the SEP proton flux-time profile from July 1, 1974 to December 31, 2017. Each vertical colored strip represents an SEP event, with different colors indicating various energy bins. Panel b shows the corresponding daily sunspot number (SSN) for the same time duration. The frequency of SEP events is positively correlated with SSN indicating solar activities.
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