Auroral proton precipitation in the low-latitude boundary layer (LLBL) equatorwards of the northern cusp in the northward IMF simulation. (a)–(c) Differential number flux of proton precipitation calculated at the dayside northern, subsolar and southern locations, respectively. The black lines show the mean precipitating energy. (d)–(f) Integral energy flux of proton precipitation calculated at the dayside northern, subsolar and southern locations, respectively. The time intervals shaded in grey indicate that the corresponding virtual spacecraft was not magnetically connected to the inner boundary of the simulation. The panel letters (a)–(f) are colour-coded to match the colours of the VDF inset axes in Figure 2 and Supplementary Animation S2. VSC: Virtual spacecraft.