The impacts of surface heterogeneity and land surface parameterization on the mesoscale processes were studied. Experiments were conducted using the Weather Research and Forecasting (WRF) model coupled with a simple (slab) land surface model (LSM), a relatively complex Noah LSM, and a land data assimilation system (LDAS) with detailed surface fields. Three heterogeneity length scales: 1, 3, and 9 km, were employed to alter land cover and land use. A series of simulations were performed over the U.S. Southern Great Plains during the summer when the soil moisture was abundant. Results indicate that both the land surface parameterizations and fine-scale surface heterogeneity affect the model simulations; and the impact of land surface parameterization is found to be more important, particularly for low frequency ( $$f<{10}^{-4} \mathrm{hz}$$ ) eddies and mesoscale circulations. Substantial variations in turbulent spectra were also noted, and the energy spectra respond nonlinearly to the changes in the heterogeneous length scales. Three important conclusions emerge: (i) more detailed land surface representation reduces uncertainty in simulations of surface fluxes via improved turbulence characterization over a heterogeneous land surface, which helps improve simulations of land–atmosphere feedbacks; (ii) the impact of land surface heterogeneity on atmospheric feedbacks can be detected in the mesoscale circulations that are roughly four times of the spatial heterogeneity scale; and (iii) the land surface heterogeneity that can influence mesoscale circulations would be a function of grid spacing in the model.