[Fwd: RE: [MITgcm-support] grid-scale noise in 1/4-deg model]

Alistair Adcroft adcroft at MIT.EDU
Wed Dec 3 13:01:14 EST 2003 

What are the CPP states of COSINEMETH_III and ISOTROPIC_COS_SCALING as used
in mom_u_yviscflux.F ?

A.
--
Dr Alistair Adcroft            http://www.mit.edu/~adcroft
MIT Climate Modeling Initiative        tel: (617) 253-5938
EAPS 54-1523,  77 Massachusetts Ave,  Cambridge,  MA,  USA

-----Original Message-----
From: mitgcm-support-bounces at mitgcm.org
[mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Ichiro Fukumori
Sent: Wednesday, December 03, 2003 11:48 AM
To: mitgcm-support at mitgcm.org
Cc: tlee at pacific.jpl.nasa.gov
Subject: RE: [Fwd: RE: [MITgcm-support] grid-scale noise in 1/4-deg model]


Yes, my mistake.  Biharmonic friction was 1.e10.  Attached is the data file
currently used.

-- Ichiro


At 10:45 AM 12/3/2003 -0500, Alistair Adcroft wrote:
>Ichiro,
>
>The quoted numbers must be for vertical viscosity? 1e-3 is way too
>small for horizontal bi-harmonic viscosity. Send me the data file for 
>the bi-harmonic run -less ambiguous that way.
>
>You can subscribe to the list by following the link on the home page:
>http://mitgcm.org/ but you don't have to subscribe to use it.
>
>A.
>--
>Dr Alistair Adcroft            http://www.mit.edu/~adcroft
>MIT Climate Modeling Initiative        tel: (617) 253-5938
>EAPS 54-1523,  77 Massachusetts Ave,  Cambridge,  MA,  USA
>
>-----Original Message-----
>From: mitgcm-support-bounces at mitgcm.org
>[mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Ichiro Fukumori
>Sent: Tuesday, December 02, 2003 6:48 PM
>To: Alistair Adcroft
>Cc: tlee at pacific.jpl.nasa.gov; mitgcm-support at mitgcm.org
>Subject: Re: [Fwd: RE: [MITgcm-support] grid-scale noise in 1/4-deg 
>model]
>
>
>Alistair,
>
>The biharmonic friction is set at 1.e-3.  The model blew up when we
>tried 2.e-3 or 5.e-3.  Should we make it smaller?
>
>  From the behavior of changing biharmonic friction and to kill the
>noise, I thought of trying a large Laplacian friction which I thought 
>would have a wider ranger of stable frictional values.  We've ran the 
>model with Laplacian viscosity of 100 and 200 (m^2/s) with cosPower=2 
>without biharmonic friction.  Case with 200 is clearly much more 
>diffusive than biharmonic with 1.e-3, but the grid-scale noise is still 
>present.
>
>KPP parameters displayed similar grid-scale noise.  So we turned
>horizontal smoothing of KPP parameters on, but the noise is still 
>present.  KPP noise must be a consequence of the grid-scale noise and 
>not the cause.
>
>We do have bottom friction on;
>   no_slip_sides=.TRUE.,
>   no_slip_bottom=.TRUE.,
>   bottomDragQuadratic = 0.002,
>in the data file.   Could we have a problem in particular advection
>scheme we are using?   We've got;
>   tempAdvScheme=4
>   saltAdvScheme=4
>   multiDimAdvection=.FALSE.,
>   staggerTimeStep=.TRUE.,
>How about CD scheme?  We don't have it on, but we tried turning it on
>cold turkey, setting D-grid velocity to zero, but the grid-scale noise 
>was still present after 30-days of integration.
>
>Any suggestions?
>
>-- Ichiro
>
>PS. I am not on the mitgcm-support mailing list.  Can I be included?
>Would I want to be included?
>
>At 03:24 PM 12/2/2003 -0800, Dimitris Menemenlis wrote:
> >-----Forwarded Message-----
> >From: Alistair Adcroft <adcroft at MIT.EDU>
> >To: mitgcm-support at mitgcm.org
> >Subject: RE: [MITgcm-support] grid-scale noise in 1/4-deg model
> >Date: Tue, 02 Dec 2003 17:10:56 -0500
> >
> >Ichiro,
> >
> >For the left column runs (bi-harmonic) were you using the maximum
> >allowed viscosity? It's worth finding the upper limit on numerical 
> >viscosity before the model is unstable. My preferred recipe is to use 
> >0.1 of this value - this damps the grid scale noise one e-folding 
> >scale every 10 steps and damps the 2-dx wave only every 160 steps. I 
> >think the relevent expression is something
> >like:
> >    A_4 * dt * cos(phi_max)^m * pi^4 [ 1 / dx(phi_max)^2 + 
> >1/dy(phi_max)^2 ]^2 < 1 assuming the expression is maximized at the 
> >northern edge of the domain. The choice of "m" can change that.
> >
> >Do you have bottom friction turned on?
> >
> >A.
> >--
> >Dr Alistair Adcroft            http://www.mit.edu/~adcroft
> >MIT Climate Modeling Initiative        tel: (617) 253-5938
> >EAPS 54-1523,  77 Massachusetts Ave,  Cambridge,  MA,  USA
> >
> >-----Original Message-----
> >From: mitgcm-support-bounces at mitgcm.org
> >[mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Ichiro 
> >Fukumori
> >Sent: Monday, November 24, 2003 9:41 PM
> >To: cnh at mit.edu; adcroft at ocean.mit.edu; support at mitgcm.org; Armin
> >Koehl; Detlef Stammer
> >Cc: tlee at pacific.jpl.nasa.gov; bnc at pacific.jpl.nasa.gov
> >Subject: [MITgcm-support] grid-scale noise in 1/4-deg model
> >
> >
> >Dear Colleagues,
> >
> >We are experiencing grid-scale noise in our global 1/4-deg model
> >simulation. It does not appear to be a lack of horizontal friction. 
> >Would you have any idea what may be the problem?  My suspicion is 
> >that this may have something to do with some vertical process.  
> >Places with prominent noise are adjacent to coastal boundaries (where 
> >there's
> >upwelling) and places with deep mixed layers.
> >
> >Attached are 2 plots comparing model output of two runs at two
> >different locations.  Each page shows a 101x101 grid point area.  
> >Plot n03d_1.ps is surface layer along the west coast of Africa 
> >(centered 13.8E, 19.4S) and the other (n03d_2.ps) is Kuroshio 
> >extension area (centered 170.1E, 28.9N) at 350m depth.  The three 
> >rows are, from the top, zonal velocity (u, m/s), meridional velocity 
> >(v, m/s), and temperature (T, degC).  The left column is a run that 
> >employs biharmonic friction (1.e10 m^4/s) and is at day 123 of 1992.  
> >The right column used Laplacian friction (200 m^2/s) and is at day 69 
> >of 1992.
> >
> >In n03d_1.ps, the noise appears along the coast (land is shown in
> >gray), especially in u & v of the right column (Laplacian friction 
> >run).
> >
> >In n03d_2.ps, the noise is severe in u & v in the left column in the
> >northern half, just south of the Kuroshio.
> >
> >All results are 3-day averages.
> >Could these noise be due to an absence of the CD scheme?  What else
> >could cause such noise?  We would appreciate any suggestions you may 
> >have.
> >
> >Thanks, Ichiro
> >
> >
> >===============================================================
> >Ichiro Fukumori               | Jet Propulsion Laboratory
> >e-mail: fukumori at jpl.nasa.gov | Mail Stop 300-323
> >phone: +1 (818) 354-6965      | 4800 Oak Grove Drive
> >fax: +1 (818) 393-6720        | Pasadena, California 91109, U.S.A.
> >===============================================================
> >
> >
> >_______________________________________________
> >MITgcm-support mailing list
> >MITgcm-support at mitgcm.org
> >http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
> >--
> >Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
> >Jet Propulsion Lab, California Insitute of Technology
> >MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
> >tel: 818-354-1656;  fax: 818-393-6720
>
>===============================================================
>Ichiro Fukumori               | Jet Propulsion Laboratory
>e-mail: fukumori at jpl.nasa.gov | Mail Stop 300-323
>phone: +1 (818) 354-6965      | 4800 Oak Grove Drive
>fax: +1 (818) 393-6720        | Pasadena, California 91109, U.S.A.
>===============================================================
>
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>
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