About non-breaking wave enhanced vertical mixing

[wrh]

It is well-known that non-breaking waves are a significant source of enhancement for eddy viscosity and heat diffusion. However, there is nothing when I search for non-breaking waves inducing mixing in the ROMS-SWAN or COAWST code. So if I want to add non-breaking waves-induced mixing in my simulation? any suggestions? thank you everyone.

[lfparejar]

I don't think ROMS/COAWST has a special treatment of breaking and non-breaking waves when it comes to mixing and TKE injection in the water column. Deep-water breaking (whitecapping) is a poorly understood phenomenon that remains a challenge to parameterize.

I know of two options to account for wave-induced mixing in a 'bulk' way, that is, including breaking and non-breaking:

In ROMS:
#define CHARNOK (Computes the roughness length scale z0 from an initial value of u*)
#define CRAIG_BANNER (this follows Craig and Banner 1994, JPO)

In COAWST (if SWAN is active)
#define ZOS_HSIG (Computes z0 based on wave height, following Stacey 1999, JPO)
#define TKE_WAVEDISS (Uses wave amplitude to calculate TKE injection).

I think that the COAWST option follows the formulation of Carniel et al 2009, Oc. Mod*, which adds a wave-induced mixing term to the surface boundary condition of TKE injection (see Olabarrieta et al, 2011 JGR doi:10.1029/2011JC007387, Eq C7). The wave-mixing factor 'Cw' depends on the sea state and is typically ~100, but I don't know if the model calculates it or if it's a constant. Without wave breaking, Cw=0 - something to look for in /ROMS/Nonlinear/gls_corstep.f90.

*Carniel, S., J. C. Warner, J. Chiggiato, and M. Sclavo (2009), Investigating the impact of surface wave breaking on modeling the trajectories of drifters in the northern Adriatic Sea during a wind‐storm event, Ocean Modell., 30, 225–239, doi:10.1016/j.ocemod.2009.07.001.

I hope this helps

FP

[wrh]

Thank you for your reply