To aid development of sub-grid scale (SGS) parameterizations for Earth system models which consider heterogeneity in land-surface fields and land-atmosphere coupling, results from large-eddy simulations of 92 shallow convection cases over the Southern Great Plains are presented and analyzed. Each case is simulated with heterogeneous surface fields obtained from an offline field-scale land-surface model, and with spatially homogeneous surface fields with the same domain-wide mean value. By comparing corresponding heterogeneous and homogeneous cases, it is found that turbulent kinetic energy and liquid water path has a high correlation with the spatial variance of the surface heat flux fields. By further comparing the source of this correlation over the range of wavelengths in the surface fields, it is found that the majority of the heterogeneous land-atmosphere coupling is contained in wavelengths of order 10 km and larger, suggesting an encouraging degree of feasibility of including land-surface heterogeneity in global-scale SGS parameterizations.