Filed capacity estimation in mo_mpr_soilmoist.f90

Please check: FC values for Germany were too low compared to available publications. Therefore I checked the code and found that the Twarakavi, et. al. 2009, WRR EQ7 differs from what is coded and therefore made changes in two lines:

elemental pure subroutine field_cap( thetaFC, & ! Output Ks, thetaS, Genu_Mual_n ) ! Input

[...]

! x = (field_cap_c1) * (field_cap_c2 + log10( Ks ))
! thetaFC = thetaS * exp( x * log(Genu_Mual_n) )

x =  field_cap_c1 * (field_cap_c2 + log10( Ks ) )  ! (Twarakavi, et. al. 2009, WRR) EQ7 exponent

thetaFC =  Genu_Mual_n ** x

The result is that FC values are in the expected range now for Germany. aET values now show lower value in summer time (~0.35mm/day) and almost unchanged in winter - please keep in mind that I did not re-calibrate the model.