Unrealistic mixing layer deepening with artificial w

[scenty]

Recently I am running a 1-D model based on bio_toy, 300 m depth. The forcing is bulk wind stress fluxes, heat and water fluxes.

We wanted to include the effect of vertical velocities from, e.g., Ekman pumping and other processes. So I modified the code (omega.F), replacing omega with prescribed vertical velocity (~10^-6 m/s). We noticed that this artificial vertical velocity would induce some non-conservation problem, so we also tested modifying the omega only in step3d_t. Both two cases showed similar problem:

The problem is that, the modification resulted in unrealistic MLD deepening.


problematic akv (larger magnitude) and temp. profiles (cyan curve is the MLD):




original akv and temp. profiles:

It is related with the vertical mixing scheme because a diagnostic plot (~150 m) shows that the temperature decreases is due to vertical mixing(red), not vertical advection (green, it is closely following the prescribed w) we added in.


We are using the LMD vmixing scheme, with:

Code: Select all

# define LMD_RIMIX
# define LMD_CONVEC
# define LMD_SKPP
# define LMD_BKPP
# define LMD_NONLOCAL

Is there anyone can figure out why the mixing scheme had such behavior? Any discussions or suggestions are appreciated!