Algebraic length-scale from ISPRAMIX


INTERFACE:

   subroutine ispralength(nlev,NN,h,depth)
DESCRIPTION:

This subroutine calculates the lengthscale used in the ISPRAMIX model, see Eifler and Schrimpf (1992) and Demirov et al. (1998). In both mixing regions (close to the surface and the bottom), $ l$ is obtained from the formula

$\displaystyle l = \frac {\kappa \tilde z} {1+\frac {\kappa \tilde z} {c_2 \cdot h_m}} (1-R_f)^e$ (183)

where $ \tilde z$ is the distance from the interface (surface or bottom). The fraction in (183) predicts an approximation to a linear behavior of $ l$ near boundaries and a value proportional to the thickness of the mixed layer far from the interface, $ l=c_2 h_m$, where $ c_2=0.065$ is estimated from experimental data as discussed in Eifler and Schrimpf (1992). The factor $ (1-R_f)$, with the flux Richardson number $ R_f=-G/P$, accounts for the effect of stratification on the length-scale. The parameter $ e$ is here a tuning parameter (pers. comm. Walter Eifler, JRC, Ispra, Italy) which is usually set to $ e=1$.


USES:

   use turbulence, only: L,tke,k_min,eps_min,xRF,kappa,cde
 
   IMPLICIT NONE
INPUT PARAMETERS:
 
   number of vertical layers
   integer,  intent(in)                :: nlev
 
   buoyancy frequency (1/s^2)
   REALTYPE, intent(in)                :: NN(0:nlev)
 
   layer thickness (m)
   REALTYPE, intent(in)                :: h(0:nlev)
 
   local depth (m)
   REALTYPE, intent(in)                :: depth
REVISION HISTORY:
   Original author(s):  Manuel Ruiz Villarreal, Hans Burchard

Karsten Bolding 2012-12-28