## wind stress

Discussion about tangent linear and adjoint models, variational data assimilation, and other related issues.

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onken
Posts: 11
Joined: Thu Feb 15, 2007 12:19 pm
Location: Helmholtz Zentrum Geesthacht

### wind stress

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

Reiner

kate
Posts: 3718
Joined: Wed Jul 02, 2003 5:29 pm
Location: IMS/UAF, USA

### Re: wind stress

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) )``````

wilkin
Posts: 510
Joined: Mon Apr 28, 2003 5:44 pm
Location: Rutgers University
Contact:

### Re: wind stress

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" http://journals.ametsoc.org/doi/abs/10. ... -15-0232.1
John Wilkin: DMCS Rutgers University
71 Dudley Rd, New Brunswick, NJ 08901-8521, USA. ph: 609-630-0559 jwilkin@rutgers.edu