[MITgcm-support] vertical velocities in high-res runs

[David Ferreira]

Andreas,
Do you see a weak stratification along these lines (DRHODR) ?
How do you force your channel from the sides, open boundary conditions 
on the East/West/North, restoring ?
I'm thinking you could be imposing a background stratification with 2 
weak spots where vertical velocities are enhanced.
david




On 8/23/12 9:43 PM, Andreas Klocker wrote:
> Hi everyone,
>
> I've got a little problem with vertical velocities in I high-res run 
> which I don't understand and I have no idea how to get rid of that 
> problem.
>
> The model is a channel with realistic topography, 1/20 deg resolution, 
> 150 vertical layers, see below data file for more info.
>
> The problem: As you can see in the attached figure of the vertical 
> velocity I always get two lines (which not quite follow isopycnals) 
> which have very strong grid-scale vertical velocities along them which 
> do not make sense. I tried both advection scheme 7 and 33 and it 
> doesn't make much of a difference. When I add more Smagorinsky visc. 
> the whole velocity filed gets much smoother and less energetic but the 
> problem of the grid-scale noise doesn't change. If I use KPP it 
> produces large vertical diff. in those regions but the problem doesn't 
> go away...I'm not sure what else to try...
>
> Has anyone got an idea what could cause that problem and how to solve it?
>
> cheers,
> Andreas
>
> # Continuous equation parameters
>  &PARM01
>  tRef               = 150*5.0,
>  sRef               = 150*34.5,
>  viscAr= 5.6614e-04,
>  diffKrT=1.e-5,
>  diffKrS=1.e-5,
>  no_slip_sides=.FALSE.,
>  no_slip_bottom=.TRUE.,
>  rhonil=1027.5,
>  rhoConstFresh=999.8,
>  eosType='JMD95Z',
> # hFacMinDr=50.,
> # hFacMin=0.5,
>  hFacInf=0.01,
>  hFacSup=2.,
>  select_rStar=2,
>  nonlinFreeSurf=4,
>  implicitDiffusion=.TRUE.,
>  implicitViscosity=.TRUE.,
> # ivdc_kappa=100.,
>  viscC4Leith=2.,
>  viscC4Leithd=2.,
>  viscC2Leith=1.5,
>  viscC2Leithd=1.5,
>  viscA4GridMax=0.5,
>  viscC2Smag=1.5,
> # viscA4=2.0E8,
> # viscAhD=60,
>  useAreaViscLength=.TRUE.,
>  sideDragFactor=0.,
> # highOrderVorticity  = .TRUE.,
>  useAbsVorticity=.TRUE.,
>  selectVortScheme=2,
>  selectKEscheme=3,
>  bottomDragQuadratic = 0.0025,
>  tempAdvScheme=7,
>  saltAdvScheme=7,
>  StaggerTimeStep=.TRUE.,
>  multiDimAdvection=.TRUE.,
>  vectorInvariantMomentum=.TRUE.,
>  implicitFreeSurface=.TRUE.,
>  exactConserv=.TRUE.,
> # debuglevel=4,
>  convertFW2Salt=-1
>  useRealFreshWaterFlux=.TRUE.,
>  useSingleCPUio=.TRUE.,
>  globalFiles=.TRUE.,
>  allowFreezing=.TRUE.,
> # useJamartWetPoints=.TRUE.,
>  &
>
>
>
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