Comparison of a snapshot in time at τ = 8.8 for a sinking bubble simulation with an initial size of b₀/H₀ = 2/5 for different choices of grid resolution, where ζ ≡ z/b₀ is the dimensionless depth. Colors correspond to the integrated line-of-sight specific entropy perturbations, i.e., ∫_Y ρδsdy, where δs is defined in Eq. (21), y is the dimension coming out of the page, and Y is its simulated domain. Units on the color bar are arbitrary, linearly proportional to entropy surface density. The dynamical instability observed for Δx ≥ b₀/40 is not observed for the lowest-resolution (leftmost) simulation, whose vortex ring remains stable until colliding with the bottom boundary of the simulation.