*INTERFACE:*

subroutine do_seagrass(nlev,dt)

Here the time depending seagrass equation suggested by Verduin and Backhaus (2000) is calculated. In order to explain the basic principle, an idealised example is examined here with a simplified momentum equation,

(269) |

and the Lagrangian tracer equation for seagrass,

(270) |

where is the Langrangian horizontal excursion of the seagrass. The seagrass friction coefficient, , is only non-zero at heights where seagrass tracers are at their excursion limits:

(271) |

The maximum excursion limits and the friction coefficients are read from a file.

The production of turbulence is calculated here as the sum of shear production and friction loss at the seagrass leaves,

which is added to the usual shear-production term as illustrated in (146). The efficiency coefficient of turbulence production by sea-grass friction, , is denoted as

*USES:*

use meanflow, only: u,v,h,drag,xP IMPLICIT NONE

integer, intent(in) :: nlev REALTYPE, intent(in) :: dt

Original author(s): Karsten Bolding & Hans Burchard

integer :: i REALTYPE :: dist REALTYPE :: grassfric(0:nlev) REALTYPE :: excur(0:nlev) REALTYPE :: z(0:nlev)

Karsten Bolding 2012-01-24