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Even though compressible plasma turbulence is encountered in manyastrophysical phenomena, its effect is often not well understood. Furthermore,direct numerical simulations are typically not able to reach the extremeparameters of these processes. For this reason, large-eddy simulations (LES),which only simulate large and intermediate scales directly, are employed. Thesmallest, unresolved scales and the interactions between small and large scalesare introduced by means of a subgrid-scale (SGS) model. We propose and verify anew set of nonlinear SGS closures for future application as an SGS model in LESof compressible magnetohydrodynamics (MHD). We use 15 simulations (withoutexplicit SGS model) of forced, isotropic, homogeneous turbulence with varyingsonic Mach number $\mathrm{M_s} = 0.2$ to $20$ as reference data for the mostextensive \textit{a priori} tests performed so far in literature. In thesetests we explicitly filter the reference data and compare the performance ofthe new closures against the most widely tested closures. These includeeddy-viscosity and scale-similarity type closures with differentnormalizations. Performance indicators are correlations with the turbulentenergy and cross-helicty flux, the average SGS dissipation, the topologicalstructure and the ability to reproduce the correct magnitude and direction ofthe SGS vectors. We find that only the new nonlinear closures exhibitconsistently high correlations (median value \textgreater$0.8$) with the dataover the entire parameter space and outperform the other closures in all tests.Moreover, we show that these results are independent of resolution and chosenfilter scale. Additionally, the new closures are effectively coefficient-freewith a deviation of less than $20\%$.

A nonlinear structural subgrid-scale closure for compressible MHD Part II: a priori comparison on turbulence simulation data