_Tracer_timestep.dox

1/*! \page Tracer_Timestep Tracer Timestep

2

3\brief Overview of Tracer Timestep

4

5The MOM6 code handles advection and lateral diffusion of all tracers. For

6potential temperature and salinity, it also timesteps the thermodynamics

7and vertical mixing (column physics). Since evaporation and precipitation

8are handled as volume changes, the layer thicknesses need to be updated:

9

10\f[

11 \frac{\partial h_k}{\partial t} = (P - E)_k

12\f]

13

14The full tracer equation for tracer \f$\theta\f$ is:

15

16\f[

17 \frac{\partial}{\partial t} (h_k\theta_k) + \nabla_s \cdot

18 (\vec{u}h_k \theta_k) = Q_k^\theta h_k + \frac{1}{h_k} \Delta \left(

19 \kappa \frac{\partial \theta}{\partial z} \right) + \frac{1}{h_k}

20 \nabla_s (h_k K \nabla_s \theta)

21\f]

22

23Here, the advection is on the left hand side of the equation while the

24right hand side contains thermodynamic processes, vertical diffusion, and

25horizontal diffusion. There is more than one choice for vertical diffusion;

26these will be described elsewhere. Also, the lateral diffusion is handled

27in novel ways so as to avoid introduction of new extrema and to avoid

28instabilities associated with rotated mixing tensors. The lateral diffusion

29is described in \ref Horizontal_Diffusion.

30

31*/