[MITgcm-support] how to modify the detail of model result

[Martin Losch]

Hi Tongya Liu,

In general, you need more information to describe your problem. As it is now, there is not much to say.

I don’t see any obvious problems in your “data” file, I cannot say too much about your obcs configuration (because you didn’t share it), and I also have no idea, what you mean by “strange eddies” (and I have no idea, what the SCS should look like anyway). Does this look like something numerical? Maybe you can put a few plots of what it looks like and what you think it should look like on some webserver to look at (please don’t send large files to this list). Does the vertical structure of the watermasses change a lot (may be a hint at something going on with vertical mixing, what do you use as mixed layer model?)

A wild guess: sometimes setting
 vectorInvariantMomentum=.TRUE.,
helps the simulations dramatically.

I find your delR not very smooth. As a rule of thumb set dr(k+1)/dr(k) < 1.4 to avoid too large inaccuracies in the vertical discretization. But I don’t think that this will help substantially.

In terms of boundary conditions: I have had good experiences with the stevens boundary conditions (see documentation).

Martin

On Jan 9, 2015, at 9:08 AM, Tongya Liu <liutongya13 at mails.ucas.ac.cn> wrote:

> Hi all,
> 
> I use the MITgcm moel to study the effect of Kuroshio on the circulation of South China Sea. The model domain is 0-30N&99-135E, and the resolution is 0.1 degree. The force field contains climatology monthly wind, SST and SSS. The eastern, northern and southern boundary are OBs and the boundary velocity originate from the u and v of HYCOM. The case run for 10 years. The model result can reflect the major features of circulation in this region,such as, NEC, NECC and Kuroshio can be easily recognized. But the details of circulation is different from the real circulation. There are many strange eddies, especially in the interior of SCS. I have no idea what is the problem. Is the setting of OBCS or viscosity parameters inappropriate?
> 
> Thanks for any advice!
> 
> Tongya Liu
> 
> data file:
> 
> # ====================
> # | Model parameters |
> # ====================
> #
> # Continuous equation parameters
>  &PARM01
>  viscAr=1.77E-3,
> &n bsp;viscAh=0,
>  diffKhT=0,
>  diffKrT=1.51E-5,
>  diffKhS=0,
>  diffKrS=1.51E-5,
>  useFullLeith=.TRUE.,
>  viscC4Leith=1.0,
>  viscC4Leithd=1.0,
>  viscA4GridMax=1.0,
> 
>  tempAdvScheme=33,
>  saltAdvScheme=33,
>  eosType = 'JMD95Z',
> 
>  no_slip_sides=.FALSE.,
>  no_slip_bottom=.TRUE.,
>  bottomDragQuadratic=0.0025,
>  implicitDiffusion=.TRUE.,
>  implicitFreeSurface=.TRUE.,
>  implicitViscosity=.TRUE.,
> 
>  staggerTimeStep=.TRUE.,
>  implicitFreeSurface=.TRUE.,
>  exactConserv=.TRUE.,
>  hFacMin=0.1,
>  readBinaryPrec=64,
> #- not safe to use globalFiles in multi-processors runs
>  globalFiles=.TRUE.,
>  useSingleCpuIO=.TRUE.,
>  &
> 
> # Elliptic solver parameters
>  &PARM02
>  cg2dMaxIters=1000,
>  cg2dTargetResidual=1.E-13,
>  &
> 
> # Time stepping parameters
>  &PARM03 nIter0=       0,
> #nIter0=       34560,
>  nTimeSteps = 2592000,
> #startTime=0.,
> #endTime=311040000.,
>  basetime=0,
>  deltaT=1200.0,
>  abEps=0.1,
>  momDissip_In_AB=.FALSE.,
>  dumpFreq=864000.0,
>  pChkptFreq=31104000.,
>  chkptFreq=2592000.,
>  monitorSelect=2,
>  monitorFreq=1200.,
> 
>  &
> 
> # Gridding parameters
>  &PARM04
>  usingSphericalPolarGrid=.TRUE.,
>  ygOrigin=0.0,
>  xgOrigin=99.,
>  dxSpacing=0.1,
>  dySpacing=0.1, 
>  delR=30.,30.,30.,30.,30.,30.,
>        30.,30.,30.,30.,30.,30.,
>        30.,30.,30.,30.,30.,30.,
>        30.,30.,50.,50.,100.,200.,
>        300.,500.,600.,800.,800.,1000.,
>  &
> # Input datasets
>  &PARM05
> & nbsp;bathyFile='topog.bin',
>  hydrogThetaFile='Temp.bin',
>  hydrogSaltFile='Salt.bin',
>  &
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support