1. In micrometeorology, the region of ground that affects a turbulent flux measurement above the surface. Also known as the source-weight distribution function, the footprint can figuratively be described as the ensemble average field-of-view of a turbulent flux measurement. The footprint function is derived from a suitable model of turbulent transport. Alternately, an analogous footprint can be defined for scalar concentrations or for radiative fluxes. 2. In remote sensing, the instantaneous field-of-view of an airborne remote sensing instrument.