[MITgcm-support] Fwd: Underestimated ETA values for Global Ocean!

Abhisek Chakraborty abhisek.sac at gmail.com
Mon Mar 25 11:18:45 EDT 2013


Respected Dr. Dimitris Menemenlis,


As per your suggestion I tried to correct my sea level and now I am getting
reasonable values for sea level elevation from MITgcm. (Attached figures
show sea levels from MITgcm as well as from NCEP GODAS).

Now I am facing another problem with SST. I found that seasonal variation
of the model SST is not so prominent (figures attached) though I am making
relaxation of the model SST to Levitus monthly climatology. Can you please
guide me to correct my model SST? (The necessary data files are attached
here).

Thanking in advance,
Abhisek


On Mon, Mar 25, 2013 at 1:28 PM, Abhisek Chakraborty
<abhisek.sac at gmail.com>wrote:

>
>
> ---------- Forwarded message ----------
> From: Abhisek Chakraborty <abhisek.sac at gmail.com>
> Date: Sat, Mar 16, 2013 at 3:01 PM
> Subject: Underestimated ETA values for Global Ocean!
> To: mitgcm-support <mitgcm-support at mitgcm.org>
>
>
>
> Dear MITgcmUsers,
>
> I am working with global ocean simulation using MITgcm. The "data" file
> configuration is
>
> # ====================
> # | Model parameters |
> # ====================
> #
> # Continuous equation parameters
>  &PARM01
>  tRef = 3*23.,3*22.,21.,2*20.,19.,2*18.,17.,2*16.,15.,14.,13.,
>                       12.,11.,2*9.,8.,7.,2*6.,2*5.,3*4.,3*3.,4*2.,12*1.,
>  sRef = 50*34.5,
> #
>  no_slip_sides=.FALSE.,
>  no_slip_bottom=.TRUE.,
> #
>  viscAr= 1.77e-5,
>  diffKhT=0.,
>  diffK4T=0.,
>  diffKrT=1.51e-5,
>  diffKhS=0.,
>  diffK4S=0.,
>  diffKrS=1.51e-5,
> #
>  viscAh=0.,
>  viscAhGrid=0.,
>  viscC2Leith=0.,
>  viscA4=0.,
>  useFullLeith=.TRUE.,
>  viscC4Leith=2.0,
>  viscC4Leithd=2.0,
>  useAnisotropicViscAGridMax=.TRUE.,
>  bottomDragQuadratic = 0.002,
> #
>  tAlpha=2.E-4,
>  sBeta =7.4E-4,
>  rhonil=1035.,
>  rhoConstFresh=1000.,
>  gravity=9.81,
>  eosType='JMD95Z',
>  readBinaryPrec=32,
>  writeBinaryPrec=32,
>  useSingleCPUio=.TRUE.,
>  globalFiles=.TRUE.,
>  hFacMinDr=50.,
>  hFacMin=0.3,
>  implicitDiffusion=.true.,
>  implicitViscosity=.true.,
>  implicitFreeSurface=.TRUE.,
>  useRealFreshWaterFlux=.true.,
>  exactConserv=.TRUE.,
>  allowFreezing=.TRUE.,
>  useCDscheme=.TRUE.,
>  useNHMTerms=.TRUE.,
> #
>  tempAdvScheme=33,
>  saltAdvScheme=33,
>  StaggerTimeStep=.true.,
>  multiDimAdvection=.true.,
>  vectorInvariantMomentum=.TRUE.,
>  rigidLid=.FALSE.,
>  debuglevel=-1
> &
>
> # Elliptic solver parameters
>  &PARM02
>  cg2dMaxIters=500,
>  cg2dTargetResidual=1.E-13,
>  &
>
> # Time stepping parameters
>  &PARM03
> # nIter0 =     420,
> # nTimeSteps = 3180,
> # 100 years of integration will yield a reasonable flow field
>  startTime  = 0.,
>  endTime    = 15552000000.,
>  deltaTmom  = 600.0,
>  deltaTtracer= 600.0,
>  deltaTClock = 86400.,
>  deltaTfreesurf= 600.,
>  tauCD =     321428.,
>  abEps = 0.1,
>  pChkptFreq= 3110400000.,
>  dumpFreq=   3110400000.,
>  taveFreq=   3110400000.,
>  monitorFreq=2592000.,
>  &
>
> # Gridding parameters
>  &PARM04
>  usingSphericalPolarGrid=.TRUE.,
>  delR=10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.01,
>  10.03, 10.11, 10.32, 10.80, 11.76, 13.42, 16.04 , 19.82, 24.85,
>  31.10, 38.42, 46.50, 55.00, 63.50, 71.58, 78.90, 85.15, 90.18,
>  93.96, 96.58, 98.25, 99.25,100.01,101.33,104.56,111.33,122.83,
>  139.09,158.94,180.83,203.55,226.50,249.50,272.50,295.50,318.50,
>  341.50,364.50,387.50,410.50,433.50,456.50,
>  ygOrigin=-80.0,
>  dySpacing=1.,
>  dxSpacing=1.,
>  &
>
> # Input datasets
>  &PARM05
>  bathyFile=      '../input/bathymetry.bin',
>  hydrogThetaFile='../input/lev_t.bin',
>  hydrogSaltFile= '../input/lev_s.bin',
>  &
>
> and the atmospheric forcings
> (atemp,aqh,uwind,vwind,swdown,lwdown,precip,runof,climsst,climsss) are
> specified through EXF package. Apart from these I am using GMRedi and KPP
> parametrisation schemes. After spinning up the model for 500 years and then
> running the model with monthly NCEP fields, I found that temperature,
> salinity, currents are matching well with GODAS (NCEP), but surface
> elevation (ETA) is underestimated (though the patterns are matching with
> GODAS). I have attached one simulation result ( you can see negative
> elevation in most of the places). Can anybody please guide me how to
> correct this?
>
> Thanking in advance,
> Abhisek
>
>
>
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