1. Kcb
   1. Kcb is replaced with Canopy based reflectance coefficient Kcrf
      1. Kcrf is linearly related to NDVI
2. Ke
   1. Calculating Soil Evaporation coefficient Ke using FAO56 method. Ke = Kr(Kc max - Kcb) <= few Kc max Kcb basal crop coefficient, Kc max maximum value of Kc following rain or irrigation, Kr dimensionless evaporation reduction coefficient dependent on the cumulative depth of water depleted (evaporated) from the topsoil and ranges from 0 to 1 for completely dry upper soil to recently irrigated soil surface. few fraction of the soil that is both exposed and wetted, i.e., the fraction of soil surface from which most evaporation occurs.
      1. Kr=(TEW-De,i-1)/(TEW-REW)
         1. TEW=1000(θFC-0.5θWP)Ze Where:- TEW is total evaporable water(mm), θFC, soil water content and θWP soil water content at wilting  point Ze is the depth of surface soil layer subjected to drying θFC,θWP and Ze can be obtaided from FAO-56 table 19.
         2. De,i-1 is the cumulative depth of evaporation from soil surface layer at the end of day i-1.
         3. REW => Readily evaporable water, it is the cumulative water depletion (mm) in the phase where evaporation is only limited by available energy. Later, evaporation rate of water from top soil decreases, as the soil surface gradually dries.
3. ET0
   1. is the grass/alfalfa reference ET on that day.
4. Ks
   1. Obtained from daily water balance at root zone.