unom Function

REAL FUNCTION unom(logdz, logdzh, logzh, sqdz, utangInt, dT, Ribl0, fkar2) !for momentum, this bit is not depended on orientation etc
!momentum flux in m2/s2
!dT,utang and logdzh are unused and could be removed
   IMPLICIT NONE
   REAL, INTENT(in) :: logdz, logdzh, logzh, sqdz, utangInt, dT, Ribl0, fkar2
   REAL :: Ribl1, Fm, Fh, cm, ch, Ctm, M
   REAL, PARAMETER :: b1 = 9.4 !parameters from Uno1995
   REAL, PARAMETER :: b2 = 4.7
   REAL, PARAMETER :: dm = 7.4
   REAL, PARAMETER :: dh = 5.3
   REAL, PARAMETER :: prandtlmol = 0.71
   IF (Ribl0 > 0.21) THEN !0.25 approx critical for bulk Richardson number  => stable
      Fm = 1./(1. + b2*Ribl0)**2 !Eq. 4
      Fh = Fm !Eq. 4
   ELSE ! => unstable
      cm = (dm*fkar2)/(logdz**2)*b1*sqdz !Eq. 5
      ch = (dh*fkar2)/(logdz**2)*b1*sqdz !Eq. 5
      Fm = 1. - (b1*Ribl0)/(1. + cm*SQRT(ABS(Ribl0))) !Eq. 3
      Fh = 1. - (b1*Ribl0)/(1. + ch*SQRT(ABS(Ribl0))) !Eq. 3
   END IF

   M = prandtlmol*logdz*SQRT(Fm)/Fh !Eq. 14

   Ribl1 = Ribl0 - Ribl0*prandtlmol*logzh/(prandtlmol*logzh + M) !Eq. 17

   !interate to get new Richardson number
   IF (Ribl1 > 0.21) THEN !0.25 approx critical for bulk Richardson number  => stable
      Fm = 1./(1. + b2*Ribl1)**2 !Eq. 4
   ELSE ! => unstable
      cm = (dm*fkar2)/(logdz**2)*b1*sqdz !Eq. 5
      Fm = 1. - (b1*Ribl1)/(1. + cm*SQRT(ABS(Ribl1))) !Eq. 3
   END IF

   Ctm = fkar2/(logdz**2)*Fm !Eq. 7
   unom = Ctm !Eq. 2, Eq. 8
END FUNCTION unom