low dissipation of energy as shown in Figure \[fig:lilly-15\] are discussed in [@andre77] and [@lilly86b] (the “epsilon” on the vertical axes in both Figure \[fig:lilly-13\] and Figure \[fig:lilly-15\] stands for the energy dissipation rate per unit mass, not the horizontal grid spacing $\varepsilon$ used in Sections \[sec:pseudovorticity\], \[sec:cm1\], and \[sec:energy\_spectrum\]). The images represent the results of two numerical experiments and show that isotropic turbulence with helicity inhibits the dissipation of energy at large scales, which is consistent with Figure \[fig:158\_zoomed-out\], Figure \[fig:vortex\_image\_time\_series1.pdf\], and Figure \[fig:lilly-15\].

![Inertially weighted energy spectrum corresponding to time $t=8$ for a turbulent flow with low helicity showing high dissipation at large scales (small $k$); © AMS, [@andre77; @lilly86b].[]{data-label="fig:lilly-13"}](lilly-energy-spectrum-low-helicity){width="85.00000%"}

![Inertially weighted energy spectrum corresponding to time $t=12$ for a turbulent flow with high helicity showing low dissipation at large scales (small $k$); © AMS, [@andre77; @lilly86b].[]{data-label="fig:lilly-15"}](lilly-energy-spectrum-high-helicity){width="85.00000%"}

Under the effects of strong rotation, the flow has the tendency to become anisotropic [@pouquet10]. Studies have shown that the presence of helicity and low-energy dissipation are unlinked unless the helicity is continuously supplied and/or generated at the energy-containing scales; this is associated with inhomogeneity in the mean field [@lilly86a; @lilly86b; @yokoi93]. Such an inhomogeneity would be supplied by surface friction 