There are a few major characteristics that make SEBAL different from other Remote Sensing flux algorithms:
- The sensible heat flux is fixed at the so called "hot" and "cold" pixel. These two points should "anchor" the the range of sensible heat flux or evaporative fraction, thus these two pixels should be divided between very dry terrain (where latent heat flux is small to zero) and very moist terrain (where sensible heat flux is small to zero).
- ΔT (i.e. the vertical difference in air temperature) is computed from inversion of the sensible heat flux at the anchor points. This implies that neither radiometric surface temperature, nor air temperature measurements are
involved in the computation of ΔT.
- ΔT is linearly related to radiometric surface temperature. This relationship depends on the satellite image chosen (area, climate, time of overpass) and is often referred to as the "self-calibration" approach.
- Surface heat flux fractions are temperate constant throughout the day. Different fractions can be thought of, such as the evaporative fraction and the relative evapotranspiration, i.e. ETa/ETref. A simple correction can be added to correct for advection effects on the evaporative fraction.
An overview of SEBAL applications is provided on a poster.