Vertical Mixing Schemes in LOAM

Large et al. (1994) K-profile parameterisation (KPP)

c     compute vertical mixing coefficients based on the k-profile
c     and oceanic planetary boundary layer scheme by large & mcwilliams.

Kraus-Turner mixing AND convective adjustment (a la dconv)

c         for use with a level grid;  includes the effect of
c         wind stirring
c
c  Uses the Kraus-Turner vertical mixing algorithm described in:
c         Stefan Rahmstorf, 1991: A zonal-averaged model of the
c         ocean's response to climate change, JGR Oceans, V.96,
c         p. 6951-6963;

Richardson number dependent mixing

c---------------------------------------------
      subroutine visc_diff (Ri, rnu, rka)
c---------------------------------------------
c     eddy viscosity & diffusivity
c     a'la Pacanowski & Philander [1981]
c---------------------------------------------
c from PP-1981:
      parameter (GAMMA = 5., RNU_0 = 0.05)
c     parameter (RNU_B = 1.e-4, RKA_B = 1.e-5)
c
c suggested by Gilles Reverdin to Senya (1992):
      parameter (RNU_B = 1.34e-5, RKA_B = 1.34e-6)
 
c added by Martin (1999), so that maximum is same as for KPP
      parameter (RNU_MAX = 0.005)
 
      parameter (RNU_NEG = RNU_B + RNU_0)
      parameter (RKA_NEG = RKA_B + RNU_NEG)
 
      if ( Ri .gt. 0. ) then
         tmp = 1. + GAMMA * Ri
         rnu = RNU_B + RNU_0 / (tmp * tmp)
         rnu = min(RNU_MAX,rnu)
         rka = RKA_B +   rnu / tmp
      else
         rnu = RNU_NEG
         rka = RKA_NEG
      endif
 
      return
      end

- Naomi Naik, January 2002