Effects of horizontal and vertical grid spacing on mixing in simulated squall lines and implications for convective strength and structure

Some storm characteristics, such as the mean convective core area, change substantially for Δh 250 m but show limited sensitivity as Δ is decreased below 250 m, despite better resolving smaller-scale turbulent motions. This transition is found to be independent of the chosen . Mixing in the context of varying Δh and Δv is also investigated via passive tracers that are initialized 1 h after restarting the simulations (i.e., after the spin up of small-scale motions).

The tracer field at the end of the simulations reveals that entrainment and detrainment are suppressed in the simulations with Δh≥ 500 m. For decreasing Δ, entrainment and detrainment are substantially more important, limiting the flux of low-level tracer to the upper troposphere, which has important implications for modeling studies of convective transport from the boundary layer through the troposphere.