jhan_JaC_Redux_JAC_5.7_Radmaster_ExtinctionCoeff

Extinction co-efficients

As usual, direct beam and diffuse components are treated differently, however here it is easiest to just use two distinct subroutines.

subroutine ExtinctionCoeff_beam(....)

! retain this initialization for bare soil

ExtCoeff_beam = 0.5

! SW beam extinction coefficient ("black" leaves, extinction neglects
! leaf SW transmittance and REFLectance):

WHERE ( sunlit_veg_mask ) & ExtCoeff_beam = xphi1 / Coszen + xphi2

! higher value precludes sunlit leaves at night. affects
! nighttime evaporation - Ticket #90 

WHERE( .NOT. sunlit_mask ) ExtCoeff_beam = 1.0e5

! Seems to be for stability only

WHERE ( abs(ExtCoeff_beam - ExtCoeff_dif ) < 0.001 ) & ExtCoeff_beam = ExtCoeff_dif + 0.001

subroutine ExtinctionCoeff_dif(....)

ExtCoeff_dif = 0.7

WHERE ( veg_mask )

  ! Extinction coefficient for diffuse radiation for black leaves:

ExtCoeff_dif = -LOG( SUM( SPREAD( CGAUSS_W, 1, mp ) * EXP( -xk * xvlai2 ), 2) ) / reducedLAIdue2snow

END WHERE