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

[Jody Klymak]

Hi Andreas,

And you are happy w/ all the other vertical velocities?  Maybe turn off the non-linear EOS and use a linear one to start? Is there something interesting about our T/S relationship at those isopycnals that could interact with JMD95Z in funny ways, i.e. produce grid scale double diffusion?  I don't think KPP or Smagorinsky would help get rid of that.  You could also look at your horizontal diffusivities (not just viscosities).  

I have to say, that your data file is full of options I've never heard of or used.  Did you think about trimming most of them out, and then adding them back in one by one until you get the physics you want?  

Good luck,  Jody

On Aug 23, 2012, at  18:43 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.,
> &
> 
> -- 
> ===============================================
> Dr. Andreas Klocker
> Research Fellow
> 
> Center of Excellence for Climate System Science
> &
> Geophysical Fluid Dynamics Group
> Research School of Earth Sciences
> Room J7.221, Jaeger 7 Building
> The Australian National University
> Canberra ACT 0200 Australia
> 
> T:     +61 2 6125 0920
> M:     +61 437 870 182
> W:     http://web.mit.edu/aklocker/www/
> skype: andiklocker
> ===============================================
> 
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--
Jody Klymak    
http://web.uvic.ca/~jklymak/