Update the dissipation length-scale

*INTERFACE:*

subroutine do_lengthscale(nlev,dt,depth,u_taus,u_taub, z0s,z0b,h,NN,SS)

Based on the value of `len_scale_method`,
this routine calls the appropriate routines for
calculating the turbulent length-scale, , and the rate of
dissipation, . The user has the choice
between several algebraic equations described in section 4.19,
and several differential transport equations for a length-scale
determining variable. At the moment, GOTM implements equations
for the rate of dissipation, described in section 4.15,
for the Mellor-Yamada model described in section 4.14, and
for the generic scale formulated by Umlauf and Burchard (2003) and described
in section 4.16. This last transport equation generalises all of the
previously mentioned models. For example, the - model
and the - model can be recovered as special cases of the
generic equation, see Umlauf and Burchard (2003).

*USES:*

IMPLICIT NONE

integer, intent(in) :: nlev REALTYPE, intent(in) :: dt,depth,u_taus,u_taub,z0s,z0b REALTYPE, intent(in) :: h(0:nlev) REALTYPE, intent(in) :: NN(0:nlev),SS(0:nlev)

Original author(s): Karsten Bolding, Hans Burchard, Manuel Ruiz Villarreal, Lars Umlauf

Karsten Bolding 2012-12-28