[MITgcm-support] Help me get rid of my noise!
Nicolas Grisouard
nicolas.grisouard at stanford.edu
Wed May 7 17:52:19 EDT 2014
Hi,
We must be talking about something different. The isopycnal slope I was
referring to (weren't you?) is in the mixed layer, outcropping near y =
-60 and dropping by 500 m within one horizontal grid cell: 50 km? If
yes, that's a 1% slope, which is actually fairly steep. And it looks
like it could be more, resolution permitting.
But if the PV is negative everywhere, I stand corrected.
Cheers,
Nico.
On Wed 07 May 2014 02:27:34 PM PDT, Ryan Abernathey wrote:
> Nico,
>
> Interesting suggestion, but I don't think that's what's going on. Keep
> in mind that the aspect ratio is tiny for this domain. That "steep"
> isopycnal still extends over ~2000 km in the horizontal. The slope is
> ~0.002. Relative vorticity is completely negligible here, and the PV
> is everywhere negative.
>
> -Ryan
>
>
> On Wed, May 7, 2014 at 4:51 PM, Nicolas Grisouard
> <nicolas.grisouard at stanford.edu
> <mailto:nicolas.grisouard at stanford.edu>> wrote:
>
> Hi,
>
> Your isopycnal slopes there look very steep, but the image is very
> squeezed too. Could it be symmetric instability? It's not supposed
> to happen at these scales, but other mixed layer instabilities are
> probably inhibited by your 2D configuration so, why not? What's
> the sign of the PV there?
>
> Nico.
>
>
> On Wed 07 May 2014 12:57:26 PM PDT, Ryan Abernathey wrote:
>
> Thanks for all your suggestions.
> I tried turning on convective adjustment with
> ivdc_kappa=1.0,
> in my data file. I also enabled
> #define ALLOW_GGL90_SMOOTH
> in GGL90_OPTIONS.h
>
> It looks like the high values of W went down a little bit over the
> slope, a slight improvement. So I guess I am satisfied that,
> as Sonia
> put it, the solution is not "pretty" but is physically correct.
>
> I am still worried about the "stripes" of high and low W
> within the
> mixed layer between -60 and -50.
>
> Thanks again,
> Ryan
>
>
>
> On Wed, May 7, 2014 at 3:14 PM, David Ferreira <dfer at mit.edu
> <mailto:dfer at mit.edu>
> <mailto:dfer at mit.edu <mailto:dfer at mit.edu>>> wrote:
>
> Patrick's right, you need to have some convection with
> ggl90, but
> in case it's not enough: have you tried activating the
> smoother in
> ggl90 ? Might help too.
> david
>
>
>
> On 5/7/14 7:52 PM, Patrick Heimbach wrote:
>
> Ryan,
>
> yes, switching on convective adjustment is still
> advised in conjunction with ggl90 (in contrast to KPP
> where the non-local term Gamma should take care of this).
>
> Cheers
> p.
>
> On May 7, 2014, at 2:43 PM, Ryan
> Abernathey<ryan.abernathey at __gmail.com
> <mailto:ryan.abernathey at gmail.com>>
> <mailto:ryan.abernathey at gmail.__com
> <mailto:ryan.abernathey at gmail.com>> wrote:
>
> Thanks for all the helpful suggestions everyone!
> I am now convinced that this isn't as "unphysical"
> as I thought.
>
> In response to Christopher's suggestions, does
> anyone know whether I should have convective
> adjustment active together with GGL90? I know for KPP
> you are supposed to turn off all convective
> adjustment. Is that also the case for GGL?
>
> Thanks again,
> Ryan
>
>
> On Wed, May 7, 2014 at 2:10 PM, Christopher L. P.
> Wolfe<christopher.wolfe at __stonybrook.edu
> <mailto:christopher.wolfe at stonybrook.edu>>
> <mailto:christopher.wolfe at __stonybrook.edu
> <mailto:christopher.wolfe at stonybrook.edu>> wrote:
>
>
> My guess that you’re seeing hydrostatic
> convection. You don’t seem to have set either cAdjFreq
> or ivdc_kappa and my understanding is that they both
> default to zero. So, your model’s trying to do
> convection through the momentum equations and the
> convective scale is smaller than your grid spacing
> (hydrostatic convection runs to the grid scale).
>
> Christopher
>
>
> On May 7, 2014, at 1:20 PM, Ryan
> Abernathey<ryan.abernathey at __gmail.com
> <mailto:ryan.abernathey at gmail.com>>
> <mailto:ryan.abernathey at gmail.__com
> <mailto:ryan.abernathey at gmail.com>> wrote:
>
> I guess my image didn't make it through on
> that last email.
>
>
>
> On Wed, May 7, 2014 at 1:11 PM, Ryan
> Abernathey<ryan.abernathey at __gmail.com
> <mailto:ryan.abernathey at gmail.com>>
> <mailto:ryan.abernathey at gmail.__com
> <mailto:ryan.abernathey at gmail.com>> wrote:
>
> Hello MITgcm Support Group,
>
> I am running a 2D model (depth and latitude)
> in a Southern Ocean configuration. I am trying to
> eliminate what appears to be unphysical grid-scale
> noise in my W field--columns of alternately very
> high and low W. This is a snapshot of W after 5
> years of spinup. This pattern is steady in time.
>
> As you can see, the noise is concentrated
> mainly (but not exclusively) over the shelf break.
> A possibly related issue is that my cg2d solver is
> relatively far from convergence:
> cg2d: Sum(rhs),rhsMax = -5.46186194609888E-05
> 6.64557830841732E-02
>
> My model is 0.5 degree resolution in latitude,
> meaning that it is relatively high resolution
> compared to the tutorials (e.g. ideal_2D_oce), but
> of course it has no eddies or any temporal
> variability at all, since it is 2D. This puts it
> in an unknown [at least to me] parameter regime.
>
> I have tried cranking the lateral viscosity
> (both laplacian and biharmonic) up as high as they
> will go. I have enabled both linear and quadratic
> bottom drag. I am NOT using the CD scheme; the
> noise was much worse with it enabled. I am NOT
> using KPP but rather GGL90. (I tried with KPP and
> it was not very different.)
>
> I would appreciate any suggestions you have
> about how to get rid of this noise and achieve
> smooth fields.
>
> Thanks,
> Ryan
>
> ####### data file ##########
> &PARM01
> useAreaViscLength=.FALSE.,
> viscAr=1.0E-03,
> viscA4=1e12,
> viscAh=1e5,
> tempAdvScheme=77,
> # KrT fields are read in from a file
> diffKrT=0.0E-5,
> diffKhT=0.0,
> diffK4T=0.0,
> staggerTimeStep=.TRUE.,
> # initial vertical profiles of T and S
> tRef=44*0.0,
> sRef=44*35.0,
> # equation of state
> eosType='LINEAR',
> rhonil=1035.,
> eosType='LINEAR',
> tAlpha=2.000000E-04,
> sBeta=0.000000E+00,
> saltStepping=.FALSE.,
> # boundary conditions
> no_slip_sides=.FALSE.,
> no_slip_bottom=.TRUE.,
> # needed for points above the U sponge layer
> (shelf)
> bottomDragLinear=1.E-3,
> bottomDragQuadratic = 0.0012
> # additional drag is done with RBCS
> # physical parameters
> gravity=9.810000E+00,
> # implicit diffusion and convective adjustment
> implicitDiffusion=.TRUE.,
> implicitViscosity=.TRUE.,
> implicitFreeSurface=.TRUE.,
> # exact volume conservation
> # exactConserv=.TRUE.,
> # C-V scheme for Coriolis term
> useCDscheme=.FALSE.,
> # partial cells for smooth topography
> hFacMin=5.000000E-02,
> # file IO stuff
> readBinaryPrec=64,
> useSingleCpuIO=.TRUE.,
> debugLevel=1,
> &
> # elliptic solver parameters
> &PARM02
> cg2dMaxIters=500,
> cg2dTargetResidual=1E-09,
> &
> # timestepping parameters
> &PARM03
> nIter0=0000172800,
> # nTimeSteps=1000,
> # nTimeSteps=12961,
> nTimeSteps=345600,
> # deltaT=3600.0,
> # deltaT=2400.,
> # deltaT=1800.0,
> deltaT=900.0,
> abEps=0.1,
> # needed for sea ice
> forcing_In_AB = .FALSE.,
> ChkptFreq=31104000.
> pChkptFreq=311040000.,
> taveFreq=311040000.0,
> dumpFreq=31104000.,
> monitorFreq=2592000.0,
> tauThetaClimRelax=2592000.0,
> dumpInitAndLast=.TRUE.,
> pickupStrictlyMatch=.FALSE.,
> &
> # gridding parameters
> &PARM04
> usingSphericalPolarGrid=.TRUE.__,
> delX=0.5,
> delY=100*0.5,
> xgOrigin=0.,
> ygOrigin=-80.,
> delR=10., 10., 10., 10., 10., 10., 10., 12.,
> 14.,
> 16., 19., 22., 26., 30., 36.,
> 42., 50., 60.,
> 72., 85., 100., 120., 140., 166.,
> 200., 200., 200.,
> 200., 200., 200., 200., 200., 200.,
> 200., 200., 200.,
> 200., 200., 200., 200., 200., 200.,
> 200., 200.
> &
> # Input datasets
> &PARM05
> bathyFile='bathyFile_shelf___2Dchan.bin',
> zonalWindFile='zonalWindFile.__bin',
>
> thetaClimFile='thetaClimFile___WOA98_2Dchan.bin',
> diffKrFile='diffKrFile___nosponge_2Dchan.bin',
>
> hydrogThetaFile='__hydrogThetaFile_WOA98_2Dchan.__bin',
>
> hydrogSaltFile='__hydrogSaltFile_WOA98_2Dchan.__bin',
> &
>
> ########## data.pkg ##############
> &PACKAGES
> useMNC = .TRUE.,
> useGMREDI = .TRUE.,
> useGGL90 = .TRUE.,
> useRBCS = .TRUE.,
> &
>
> ######## data.gmredi ##############
> &GM_PARM01
> GM_MNC = .FALSE,
> GM_AdvForm = .TRUE.,
> GM_UseBVP = .TRUE.,
> GM_background_K = 2000,
> GM_isopycK = 2000,
> GM_Kmin_horiz = 50,
> GM_taper_scheme = 'dm95',
> GM_BVP_ModeNumber = 1,
> GM_BVP_cMin = .1,
> &end
>
> ########### data.ggl90 ############
> &GGL90_PARM01
> GGL90writeState=.FALSE.,
> GGL90TKEmin = 1.e-7,
> mxlMaxFlag=2,
> GGL90mixingLengthMin=3.,
> &
>
>
> ############ SIZE.h ##############
> ...
> PARAMETER (
> & sNx = 1,
> & sNy = 100,
> & OLx = 4,
> & OLy = 4,
> & nSx = 1,
> & nSy = 1,
> & nPx = 1,
> & nPy = 1,
> & Nx = sNx*nSx*nPx,
> & Ny = sNy*nSy*nPy,
> & Nr = 44)
> ...
>
>
>
> <W.png>_________________________________________________
>
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> <mailto:MITgcm-support at mitgcm.org>
> <mailto:MITgcm-support at mitgcm.__org
> <mailto:MITgcm-support at mitgcm.org>>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> <mailto:MITgcm-support at mitgcm.org>
> <mailto:MITgcm-support at mitgcm.__org
> <mailto:MITgcm-support at mitgcm.org>>
>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> <mailto:MITgcm-support at mitgcm.org>
> <mailto:MITgcm-support at mitgcm.__org
> <mailto:MITgcm-support at mitgcm.org>>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
> ---
> Patrick Heimbach |heimbach at mit.edu
> <mailto:heimbach at mit.edu> <mailto:heimbach at mit.edu
> <mailto:heimbach at mit.edu>> |http://www.mit.edu/~heimbach
>
> MIT | EAPS 54-1420 | 77 Massachusetts Ave | Cambridge
> MA 02139 USA
> FON+1-617-253-5259 <tel:%2B1-617-253-5259>
> <tel:%2B1-617-253-5259> | FAX+1-617-253-4464
> <tel:%2B1-617-253-4464> <tel:%2B1-617-253-4464> | SKYPE
> patrick.heimbach
>
>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> <mailto:MITgcm-support at mitgcm.org>
> <mailto:MITgcm-support at mitgcm.__org
> <mailto:MITgcm-support at mitgcm.org>>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org <mailto:MITgcm-support at mitgcm.org>
> <mailto:MITgcm-support at mitgcm.__org
> <mailto:MITgcm-support at mitgcm.org>>
>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
>
>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org <mailto:MITgcm-support at mitgcm.org>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
>
> --
> --
> Nicolas Grisouard - Postdoctoral Scholar
> Stanford School of Earth Sciences
> 473 via Ortega - room M11
> Stanford, CA 94305-4216
> Dept. fax: (+1) 650-498-5099 <tel:%28%2B1%29%20650-498-5099>
> Office Skype ID: nicolas.grisouard
> http://nicolas.grisouard.free.__fr <http://nicolas.grisouard.free.fr>
> http://www.mendeley.com/__profiles/nicolas-grisouard/
> <http://www.mendeley.com/profiles/nicolas-grisouard/>
>
> _________________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org <mailto:MITgcm-support at mitgcm.org>
> http://mitgcm.org/mailman/__listinfo/mitgcm-support
> <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>
>
>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support
--
--
Nicolas Grisouard - Postdoctoral Scholar
Stanford School of Earth Sciences
473 via Ortega - room M11
Stanford, CA 94305-4216
Dept. fax: (+1) 650-498-5099
Office Skype ID: nicolas.grisouard
http://nicolas.grisouard.free.fr
http://www.mendeley.com/profiles/nicolas-grisouard/
More information about the MITgcm-support
mailing list