Figure 2. A representative example of the reversed proton energy spectrum at L = 3.15 based on the RBSPICE measurements at 02:04:47 UT on 29 March 2015. Four characteristic parameters of the reversed energy spectrum, i.e., flux maximum (f max), flux minimum(f min), the energy of flux maximum (Emax), and the energy of flux minimum (Emin), are defined on the plot.