Update turbulence production


INTERFACE:

   subroutine production(nlev,NN,SS,xP)
DESCRIPTION:

This subroutine calculates the production terms of turbulent kinetic energy as defined in (154) and the production of buoayancy variance as defined in (161). The shear-production is computed according to

$\displaystyle P = \nu_t (M^2 + \alpha_w N^2) + X_P \; , \quad$ (148)

with the turbulent diffusivity of momentum, $ \nu_t$, defined in (46). The shear-frequency, $ M$, is discretised as described in section 3.13. The term multiplied by $ \alpha_w$ traces back to a parameterisation of breaking internal waves suggested by Mellor (1989). $ X_P$ is an extra production term, connected for example with turbulence production caused by sea-grass, see (274) in section 10.1. xP is an optional argument in the FORTRAN code.

Similarly, according to (80), the buoyancy production is computed from the expression

$\displaystyle G=-\nu^B_t N^2 + \tilde{\Gamma}_B \; , \quad$ (149)

with the turbulent diffusivity, $ \nu^B_t$, defined in (46). The second term in (149) represents the non-local buoyancy flux. The buoyancy-frequency, $ N$, is discretised as described in section 3.14.

The production of buoyancy variance by vertical meanflow gradients follows from (80) and (149)

$\displaystyle P_b = -G N^2 \quad .$ (150)

Thus, according to the definition of the potential energy (52), the buoyancy production $ G$ describes the conversion between turbulent kinetic and potential energy in (152) and (160), respectively.


USES:

   use turbulence, only: P,B,Pb
   use turbulence, only: num,nuh
   use turbulence, only: alpha,iw_model
   IMPLICIT NONE
INPUT PARAMETERS:
 
   number of vertical layers
   integer,  intent(in)                :: nlev
 
   boyancy frequency squared (1/s^2)
   REALTYPE, intent(in)                :: NN(0:nlev)
 
   shear-frequency squared (1/s^2)
   REALTYPE, intent(in)                :: SS(0:nlev)
 
   TKE production due to seagrass
   friction (m^2/s^3)
   REALTYPE, intent(in), optional      :: xP(0:nlev)
REVISION HISTORY:
   Original author(s): Karsten Bolding, Hans Burchard

Karsten Bolding 2012-12-28