2010-10-17T17:42:40+02:00 (11 years ago)

ticket:#658 minor corrections in TRA chapter

1 edited


  • branches/nemo_v3_3_beta/DOC/TexFiles/Chapters/Chap_TRA.tex

    r2285 r2286  
    8383by using the following equality : $\nabla \cdot \left( \vect{U}\,T \right)=\vect{U} \cdot \nabla T$  
    8484which results from the use of the continuity equation, $\nabla \cdot \vect{U}=0$ or  
    85 $ \partial _t e_3 + e_3\;\nabla \cdot \vect{U}=0$ in constant or variable volume case, respectively.  
     85$ \partial _t e_3 + e_3\;\nabla \cdot \vect{U}=0$ in constant volume or variable volume case, respectively.  
    8686Therefore it is of paramount importance to design the discrete analogue of the  
    8787advection tendency so that it is consistent with the continuity equation in order to  
    152152which is advected} 
    153153, implying that false extrema are permitted. Their use is not recommended on passive tracers ;  
    154 (3) It is highly recommended that the same advection-diffusion scheme is  
     154(3) It is recommended that the same advection-diffusion scheme is  
    155155used on both active and passive tracers. Indeed, if a source or sink of a  
    156156passive tracer depends on an active one, the difference of treatment of  
    157157active and passive tracers can create very nice-looking frontal structures  
    158 that are pure numerical artefacts.  
    160 \sgacomment{not sure whether 3 is still relevant after TRA-TRC branch is merged in?} 
     158that are pure numerical artefacts. Nevertheless, most of our users set a different  
     159treatment on passive and active tracers, that's the reason why this possibility  
     160is offered. We strongly suggest them to perform a sensitivity experiment  
     161using a same treatment to assess the robustness of their results. 
    161163% ------------------------------------------------------------------------------------------------------------- 
    162164%        2nd order centred scheme   
    185187with coarse resolution, and the vicinity of ice cover area ($i.e.$ when the ocean  
    186188temperature is close to the freezing point). 
    187 This combined scheme has been included for specific grid points in the ORCA2 and ORCA4 configurations only. 
     189This combined scheme has been included for specific grid points in the ORCA2  
     190and ORCA4 configurations only. This is an obsolescent feature as the recommended  
     191advection scheme for the ORCA configuration is TVD (see  \S\ref{TRA_adv_tvd}). 
    189193Note that using the cen2 scheme, the overall tracer advection is of second  
    666670In the current version, the situation is a little bit more complicated. } 
    667672The surface module (\mdl{sbcmod}, see \S\ref{SBC}) provides the following  
    668673forcing fields (used on tracers): 
    864869non-zero heat flux across the seafloor that is associated with solid  
    865870earth cooling. This flux is weak compared to surface fluxes (a mean  
    866 global value of $\sim0.1\;W/m^2$ \citep{Stein_Stein_Nat92}), but it is  
    867 systematically positive \sgacomment{positive definite?} and acts on the densest water masses.  
     871global value of $\sim0.1\;W/m^2$ \citep{Stein_Stein_Nat92}), but it warms  
     872systematically the ocean and acts on the densest water masses.  
    868873Taking this flux into account in a global ocean model increases 
    869874the deepest overturning cell ($i.e.$ the one associated with the Antarctic  
    910915implementation of the BBL, only the tracers are modified, not the velocities.  
    911916Furthermore, it only connects ocean bottom cells, and therefore does not include  
    912 the improvements introduced by \citet{Campin_Goosse_Tel99}. 
     917all the improvements introduced by \citet{Campin_Goosse_Tel99}. 
    914919% ------------------------------------------------------------------------------------------------------------- 
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