effect of some lines

[pooran]

Dear
i have seen COAWST example. Just 2 of them have following lines (rip current and inlet)

Code: Select all

 !Constants used in surface turbulent kinetic energy flux computation.
 CHARNOK_ALPHA == 1400.0d0            ! Charnok surface roughness
 ZOS_HSIG_ALPHA == 0.5d0               ! roughness from wave amplitude
       SZ_ALPHA == 0.02d0              ! roughness from wave dissipation
      CRGBAN_CW == 100.0d0             ! Craig and Banner wave breaking
      WEC_ALPHA == 0.50d0              ! 0: all wave dissip goes to break and none to roller.
                                       ! 1: all wave dissip goes to roller and none to breaking.

would you please tell me what the effect of those lines are? What happen if we eliminate them and when they are important?
thanks

[jcwarner]

please see
Implementation of the vortex force formalism in the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system for inner shelf and surf zone applications
N. Kumar, G. Voulgaris, J.C. Warner, M. Olabarrieta
Ocean Modelling, 47, (2012) 65-95

[pooran]

Dear warner
thanks. With regard that article it seems that those lines are important when we have coupling with roms and swan in VF formulation (is it true?). But it is my fault that i keep those lines when i run just roms model. Would you please tell me that it cause error in result or because i just define roms model in header file , those will be eliminate automatically.
Many thanks

[jcwarner]

these lines are used for enhanced surface roughenss due to wave breaking in GLS:
CHARNOK_ALPHA == 1400.0d0 ! Charnok surface roughness
CRGBAN_CW == 100.0d0 ! Craig and Banner wave breaking
ZOS_HSIG_ALPHA == 0.5d0 ! roughness from wave amplitude
SZ_ALPHA == 0.02d0 ! roughness from wave dissipation

and htis is used during the WEC formulations:
WEC_ALPHA == 0.50d0 ! 0: all wave dissip goes to break and none to roller.
! 1: all wave dissip goes to roller and none to breaking.

These are listed in the ROMS/Include/cppdefs.h
if you did not have these options activated, then the parameters do not do anyting.
-j

[pooran]

Thanks.
Are you mean that whenever CHARNOk and ZOH_HSIG options be defined in header file then CHARNOK_ALPHA and ZOS_HSIG_ALPHA will be used, respectively?
Sorry but i cant fined any thing about and CRGBAN_CW and SZ_ALPHA?are they related to CHARNOk and ZOH_HSIG options , respectively?
Sorry for continues questions
many thanks for your attention
cheers
pooran

[pooran]

sorry
i hope to receive your answer. i cant find my answer not in manual nor in cppdefs.h.
cheers
pooran

[jcwarner]

When uisng the GLS there are several options for surface boundary conditions for tke and gls.
Some are described in Carniel etal 2009 Ocean Modeling pp 225-239, and look at Eq 9. All bc's are described in the Kumar etal 2012 paper.

For tke the surface condition has 3 options:
- default option is just tke=u*^2/cu0^2. no cppdefs are required.
- if you define CRAIG_BANNER, then tke is a more complicated expression, but needs a 'cw' term. So that is the CRGBAN_CW in the input file. see Carniel eq 9.
- if you define TKE_WAVEDISS, then the tke surface bc is more for a surf zone type application, as described in Kumar et al and needs a coefficient to determine the portion of wave dissipation to use as tke flux. This is the sz_alpha coeff.

For gls:
it needs a surface roughness.
- the defualt is Zos_min (input file parameter).
- If you activated CRAIG_BANNER, then also define CHARNOK and that needs charnok_alpha.
- If you activated TKE_WAVEDISS, then also define ZOS_HSIG, this will be the coefficient to multiply against Hsig.

You can also look in the code:
ROMS/Nonlinear/gls_corstep.F and down around lines 800 or so you will see all these things.

-john