wind stress

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wind stress

#1 Post by onken » Fri Jan 12, 2018 4:01 pm

Is the wind stress calculation in ROMS corrected with the water velocity at the sea surface?


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Re: wind stress

#2 Post by kate » Fri Jan 12, 2018 4:09 pm

No, the default bulk_flux is not corrected for the ocean velocity. It's not that hard to do, though, and the bulk_flux I use does have it:

Code: Select all

          vmag   = max(umin, sqrt( (Uwind(i,j)-u(i,j,N(ng),nrhs))**2 +  & 
     &                             (Vwind(i,j)-v(i,j,N(ng),nrhs))**2) )

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Re: wind stress

#3 Post by wilkin » Sun Jan 14, 2018 2:50 am

In bulk_flux.F the components Uwind,Vwind are defined at rho points, not the staggered u,v points, so better code would be:

Code: Select all

          Uwind(i,j)=Uwind(i,j)-0.5_r8*                                 &
     &               (u(i,j,N(ng),nrhs)+u(i+1,j,N(ng),nrhs))
          Vwind(i,j)=Vwind(i,j)-0.5_r8*                                 &
     &               (v(i,j,N(ng),nrhs)+v(i,j+1,N(ng),nrhs))
Also, it is better to modify Uwind,Vwind directly at the beginning of bulk_flux.F because the sign of the components is subsequently used to determine the direction of the stress vector.

In very strong tidal flows (in our experience, Georges Bank and Gulf of Maine) the current is sufficient to reverse the direction of the stress in many instances.

Related to this issue of the ocean surface current feedback to the atmosphere there is a nice recent (2016) paper by Renault et al. "Modulation of Wind Work by Oceanic Current Interaction with the Atmosphere" ... -15-0232.1
John Wilkin: DMCS Rutgers University
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