%  function [Ft] = calc_Ft(Te,Ta,To)
%
    function [Ft] = calc_Ft(Te,Ta,Ts)
    
%Read parameters
  Param

%Compute emissivity of atmospheric column
  EPSA = calc_EPSA(Ta);
  
%TOA flux
  Ftdown = SIGMA*Te^4;
  Ftup = SIGMA*(EPSA*Ta^4+(1-EPSA)*Ts^4);
  Ft = Ftdown-Ftup; %>0 downward