Validation of remote sensing of bare soil ground heat flux

Ground heat flux is an important component of the energy balance in bare soils or sparsely vegetated areas. This study presents the results of a validation experiment of a remote sensing method for ground heat flux. A heat diffusion model, calibrated to local soil heat flux soil temperature profile measurements at an eddy covariance flux station in Spain, was used to validate the remote sensing method. The high energy balance closure of 93% at the site, the high correspondence of modelled temperature profile data to observations, and agreement of retrieved thermal properties with literature data gave confidence in the validation target. The remote sensing method makes use of retrieved radiometric temperatures and night-time net radiation. It was applied to field radiometry measurements over bare soil and to MSG-SEVERI data (10% of the pixel of the field site was covered by vegetation). Despite its simplicity, the remote sensing model applied to the field radiometry performed well (slope of the regression against the validation target: 1.00, r2 = 0.96). Good agreement was also found between the remote sensing method applied to field radiometry and to satellite data (slope of the regression: 0.79, r2 = 0.89).