Peak-intensity spectra for simulations with the effect of drifts included and for observers in a 700 km s⁻¹ solar wind, located at different radial distances and latitudes, as indicated by the legend. Left and right panels are for injection intensities j ∝ E⁻¹ and j ∝ E⁻³, respectively. The dotted curves are linear fits with the slope a and its standard error given in Table 2. We note that the orange line covers the blue line for the observers at 0.3 AU (dot symbols).