Histograms of the rise times of SEP events observed by the Tianwen-1/MEPA instrument at the orbit of Mars in different energy channels. Panels (a)–(o) correspond to 15 energy intervals spanning 2−100 MeV. In each panel, the blue histogram (bin width fixed at 250 minutes) represents the rise time distributions, while the red curve shows the log-normal fitting of the distribution. The legend in each panel lists the number of events we analyzed, the mean and SD of the observed rise times, and the fitted log-normal parameters with the median and shape parameter defined in Eq. (2).