Pass roughness to SWAN?

[nganju]

Right now ROMS does not pass bed roughness to SWAN. In a case with changing ripple dimensions, the roughness field should be passed to SWAN to adequately represent the effect of bed friction on the wave field. This seems straightforward, except a calculation would need to be done internally to convert Zo into a Madsen kN. Also, it appears that zo is calculated at each location individually (as opposed to Zo(i,j)) within the BBL routines, so I don't know if the roughness field can be passed as-is.

[jcwarner]

I modified the exchnage routines to allow bottom roughness to be sent from roms to swan. If a bbl is activated, then roms sends zoNik. If a bbl is not activated, roms sends rdrg2. The following files needed to be modified. swanmain.F swanpre1.F waves_coupler.F mct_roms_swan.h coupling_inlet_test.in coupling_test_head.in swan_inlet_test.in swan_test_head.in coupling.dat + i modiifed the swan.in wiki page. Hernan- i am sending these files to you via email. This trac system had a limit on the max file size.

[arango]

Done. We are now passing bottom roughness as a 2D array. The coupling routine mct_roms_swan.h now has:

         CASE ('ZO')                   ! bottom roughness

            DO j=JstrR,JendR
              DO i=IstrR,IendR
#ifdef BBL_MODEL
                Awrk(i,j)=MAX(0.0001_r8,                                &
     &                        OCEAN(ng)%bottom(i,j,izNik)*30.0_r8)
#else
                Awrk(i,j)=MAX(0.0001_r8,rdrg2(ng))
#endif
              END DO
            END DO
            CALL ROMS_export2d (ng, tile,                               &
     &                          id, gtype, scale, add_offset,           &
     &                          LBi, UBi, LBj, UBj,                     &
     &                          Awrk,                                   &
     &                          Fields(id)%ExpMin, Fields(id)%ExpMax,   &
     &                          Asize, A,                               &
     &                          status)
            CALL AttrVect_importRAttr (ocn2wav_AV, TRIM(code), A, Asize)
            Iexport=Iexport+1

Notice that the input coupling script now has ZO:

!   Field   Export    Import
!
!   NONE    -         -                 No field to import or export
!   Pair    atmos     ocean             surface air pressure
!   Tair    atmos     ocean             surface air temperature
!   Hair    atmos     ocean             surface air relative humidity
!   cloud   atmos     ocean             cloud fraction
!   SWrad   atmos     ocean             shortwave radiation flux
!   LWrad   atmos     ocean             longwave radiation flux
!   rain    atmos     ocean             rain fall rate
!   Uwind   atmos     ocean, waves      surface U-wind component
!   Vwind   atmos     ocean, waves      surface V-wind component
!   heat    atmos     ocean             surface net heat flux
!   Ustr    atmos     ocean             surface U-momentum stress
!   Vstr    atmos     ocean             surface V-momentum stress
!   SST     ocean     atmos             sea surface temperature
!   bath    ocean     waves             bathymetry
!   SSH     ocean     waves             free-surface
!   Ubar    ocean     waves             vertically integrated U-momentum
!   Vbar    ocean     waves             vertically integrated V-momentum
!   ZO      ocean     waves             bottom roughness
!   Wdir    waves     ocean             wave direction
!   Wamp    waves     ocean             significant wave height
!   Wlen    waves     ocean             average wave length
!   Wptop   waves     ocean             surface wave relative peak period
!   Wpbot   waves     ocean             bottom wave period
!   Wdiss   waves     ocean             wave energy dissipation
!   Wbrk    waves     ocean             percent wave breaking
!   Wubot   waves     ocean             wave bottom orbital velocity

Many thanks to John Warner for helping coding the new export/import field.