Conversion efficiency of injected Alfvén wave energy to outgoing FMS wave energy using ﹩{N}_{r}({N}_{{R}_{* }})\times {N}_{\theta }=4992(128)\times 400﹩. Panel (a) shows the conversion efficiency for seed Alfvén waves packets of cT/λ = 0.5. The red line denotes a single Alfvén wave injected in the northern hemisphere, black and gray lines show conversion efficiencies for seed Alfvén waves in both the northern and the southern hemispheres. Panel (b) displays conversion efficiencies of Alfvén wave interactions normalized to the efficiency of a single wave. We show different wavelengths of the injected Alfvén wave (black and blue color) and in-phase vs. out-of-phase wave injection in the two hemispheres (thick and thin lines, respectively).