Tidal Potential (sbctide.F90)

&nam_tide      !   tide parameters (#ifdef key_tide)
   ln_tide_pot   = .true.   !  use tidal potential forcing
   ln_tide_ramp  = .false.  !
   rdttideramp   =    0.    !
   clname(1)     = 'DUMMY'  !  name of constituent - all tidal components must be set in namelist_cfg

A module is available to compute the tidal potential and use it in the momentum equation. This option is activated when key_ tide is defined.

Some parameters are available in namelist nam_tide:

- ln_tide_pot activate the tidal potential forcing

- nb_harmo is the number of constituent used

- clname is the name of constituent

The tide is generated by the forces of gravity ot the Earth-Moon and Earth-Sun sytem; they are expressed as the gradient of the astronomical potential ( $ \vec{\nabla}\Pi_{a}$).

The potential astronomical expressed, for the three types of tidal frequencies following, by :
Tide long period :

$\displaystyle \Pi_{a}=gA_{k}(\frac{1}{2}-\frac{3}{2}sin^{2}\phi)cos(\omega_{k}t+V_{0k})$ (7.3)

diurnal Tide :

$\displaystyle \Pi_{a}=gA_{k}(sin 2\phi)cos(\omega_{k}t+\lambda+V_{0k})$ (7.4)

Semi-diurnal tide:

$\displaystyle \Pi_{a}=gA_{k}(cos^{2}\phi)cos(\omega_{k}t+2\lambda+V_{0k})$ (7.5)

$ A_{k}$ is the amplitude of the wave k, $ \omega_{k}$ the pulsation of the wave k, $ V_{0k}$ the astronomical phase of the wave $ k$ to Greenwich.

We make corrections to the astronomical potential. We obtain :

$\displaystyle \Pi-g\delta = (1+k-h) \Pi_{A}(\lambda,\phi)$ (7.6)

with $ k$ a number of Love estimated to 0.6 which parameterised the astronomical tidal land, and $ h$ a number of Love to 0.3 which parameterised the parameterisation due to the astronomical tidal land.

Gurvan Madec and the NEMO Team
NEMO European Consortium2017-02-17