5.1.8  Actual Evapotranspiration

 Actual evapotranspiration equals PET during the wet season (i.e., during months where potential percolation is greater than zero).  During the dry season, AET is the sum of maximum percolation (i.e., precipitation less overland runoff) and the amount of moisture withdrawn from storage (i.e., the negative of the change in soil moisture storage):



where    E_aj  is the actual evapotranspiration for the j-th month (cm).