%  function [PSIa] = calc_Psia(Ts1,Ts2)
%
    function [Psia] = calc_Psia(Ts1,Ts2)
 
 %Read parameters
 TwoBox_Param
   
%Dynamical parameterization
if HORCONV == 1 
 if Ts1-Ts2>DTcrit_circ
   Psia = BIGONE * (Ts1-Ts2-DTcrit_circ) * SV; %mass transport in kg/s 
 else
   Psia = 0;
 end
 Psio = FRACPSI * Psia;
else
    Psia = KEFF*(1+0.1*randn(1)) * (Ts1-Ts2); %in kg/s
    Psio = KEFF*(Ts1-Ts2)*FRACPSI;
end