[MITgcm-support] Spurious internal buoyancy minima in long runs
Jody Klymak
jklymak at uvic.ca
Mon Apr 25 16:27:26 EDT 2011
Hi Christopher,
Dumb question, but are you sure the diffKrNrS, and NrT are working and
being read in? You could try sticking a negligible salt anomaly in at
1800 m and see if it diffuses away in the expected time scale.
I'd also assume you are starting with a cold ocean. I personally
think that is a great approach, but maybe if your tried with a warm
ocean first to see if there is a hysteresis to this response?
A picture of your basin temperatures would be interesting as well.
Cheers, Jody
On Apr 25, 2011, at 12:33 PM, Christopher L. Wolfe wrote:
>
> Chris,
>
> The problem persists if I turn off GM/Redi (i.e. usingGMRedi=.False.
> in data.pkg). Even after more than 4000 years of integration, the
> bottom buoyancy is about 0.004 m/s^2 lower than the minimum surface
> buoyancy (bottom buoyancy is 0.003 m/s^2 vs minimum surface buoyancy
> of 0.0072 m/s^2).
>
> Christopher
>
> On Apr 21, 2011, at 8:56 AM, Chris Hill wrote:
>
>> Christopher,
>>
>> Does the same happen without GM/Redi?
>> Obviously the solution is not that useful then, but it would help
>> figure out whats going on.
>>
>> Chris
>>
>> On Wed, Apr 20, 2011 at 11:52 PM, Christopher L.P. Wolfe
>> <clwolfe at ucsd.edu> wrote:
>>>
>>> Hi Jean-Michel,
>>>
>>> Here's my data.gmredi. I've already got GM_AdvForm=.TRUE.
>>>
>>> &GM_PARM01
>>> GM_background_K = 400,
>>> GM_taper_scheme = 'dm95',
>>> GM_AdvForm = .TRUE.,
>>> GM_UseBVP = .TRUE.,
>>> GM_BVP_ModeNumber = 2,
>>> GM_BVP_cMin = .1,
>>> &
>>>
>>> Thanks,
>>> Christopher
>>>
>>>
>>>
>>> On Apr 20, 2011, at 6:34 PM, Jean-Michel Campin wrote:
>>>
>>>> Hi Christopher,
>>>>
>>>> Might be usefull to also send your data.gmredi file.
>>>> Sometime turning on "GM_AdvForm=.TRUE.," helps.
>>>>
>>>> Cheers,
>>>> Jean-Michel
>>>>
>>>> On Wed, Apr 20, 2011 at 06:04:15PM -0700, Christopher L. Wolfe
>>>> wrote:
>>>>> support] Spurious internal buoyancy minima in long runs
>>>>> X-SA-Exim-Version: 4.2.1 (built Sun, 08 Nov 2009 07:31:22 +0000)
>>>>> X-SA-Exim-Scanned: Yes (on ocean.mit.edu)
>>>>> Status: O
>>>>> Content-Length: 4534
>>>>> Lines: 150
>>>>>
>>>>> Hi Modelers,
>>>>>
>>>>> I'm having a bit of a strange problem the MITgcm. I'm running at
>>>>> coarse resolution (80 km) in a simple domain (a 2000 km by 8000
>>>>> km by 2000 m box) with a linear equation of state, GM/Redi
>>>>> eddies, and a "mixed layer" modeled by specifying a large
>>>>> diffusivity near the surface which smoothly decays into the
>>>>> interior. I'm forcing it with smooth winds, temperature
>>>>> restoring (9 days) to a fixed profile, and a fixed and balanced
>>>>> surface salt flux.
>>>>>
>>>>> The problem is that I keep ending up with bottom water which is
>>>>> denser than any water found at the surface. Both the temperature
>>>>> and salinity fields are bounded by their surface values, which
>>>>> is expected since both tracers satisfy advection-diffusion
>>>>> equations with extremum principles which state that any extrema
>>>>> are found at the surface. With a linear equation of state, the
>>>>> buoyancy satisfies a similar advection-diffusion equation with a
>>>>> similar extremum principle, yet the buoyancy of the bottom water
>>>>> is persistently lower than any water found at the surface. This
>>>>> is a serious problem, since I'm trying to study deep
>>>>> stratification and it's hard to draw any useful conclusions with
>>>>> a huge volume of my domain filled with an "impossible" water mass.
>>>>>
>>>>> I don't think this is a problem with my initial conditions,
>>>>> since I've integrated the model for almost 17,000 years with an
>>>>> interior diffusivity of 8e-5. I've tried using different
>>>>> advection schemes (2, 7, and 81) and en/disabling the
>>>>> "Smolarkiewicz hack" without any change in the results. For the
>>>>> nonlinear advection schemes, I've also varied the horizontal
>>>>> diffusivity from 0 to 100 with no effect.
>>>>>
>>>>> I'm very much bothered by this problem and have run out of
>>>>> things I can think of trying. If anyone here has any suggestions/
>>>>> explanations, I'd be extremely grateful to hear them. I'm
>>>>> enclosing my data file below for reference.
>>>>>
>>>>> Thanks,
>>>>> Christopher
>>>>>
>>>>> # ====================
>>>>> # | Model parameters |
>>>>> # ====================
>>>>> #
>>>>> # Continuous equation parameters
>>>>> &PARM01
>>>>> sRef=20*35,
>>>>> tRef=20*0.0,
>>>>> viscAh=10E3,
>>>>> viscAz=0.25E-3,
>>>>> no_slip_sides=.TRUE.,
>>>>> no_slip_bottom=.FALSE.,
>>>>> diffK4S=0.0,
>>>>> diffKhS=0.0,
>>>>> diffKzS=0.0,
>>>>> diffK4T=0.0,
>>>>> diffKhT=0.0,
>>>>> diffKzT=0.0,
>>>>> f0=-1.3683e-04,
>>>>> beta=3.4208e-11,
>>>>> tAlpha=2.E-4,
>>>>> sBeta =7.4e-4,
>>>>> gravity=10.,
>>>>> rhoConst=1000.,
>>>>> rhoNil=1000.,
>>>>> rigidLid=.FALSE.,
>>>>> implicitFreeSurface=.TRUE.,
>>>>> saltAdvection=.TRUE.,
>>>>> saltForcing=.TRUE.,
>>>>> saltStepping=.TRUE.,
>>>>> tempAdvection=.TRUE.,
>>>>> tempForcing=.TRUE.,
>>>>> tempStepping=.TRUE.,
>>>>> eosType='LINEAR',
>>>>> nonHydrostatic=.FALSE.,
>>>>> momAdvection=.TRUE.,
>>>>> implicitViscosity=.TRUE.,
>>>>> implicitDiffusion=.TRUE.,
>>>>> ivdc_kappa=10.,
>>>>> readBinaryPrec=64,
>>>>> writeBinaryPrec=32,
>>>>> tempAdvScheme=81,
>>>>> saltAdvScheme=81,
>>>>> staggerTimeStep=.TRUE.,
>>>>> bottomDragLinear=1.1135E-3,
>>>>> debugLevel=-1,
>>>>> useJamartWetPoints=.TRUE.,
>>>>> useSingleCpuIo=.TRUE.,
>>>>> diffKrNrS=4.069423e-03,
>>>>> 3.808919e-03,
>>>>> 2.924517e-03,
>>>>> 1.608878e-03,
>>>>> 5.410003e-04,
>>>>> 1.345410e-04,
>>>>> 8.147859e-05,
>>>>> 8.000402e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> diffKrNrT=4.069423e-03,
>>>>> 3.808919e-03,
>>>>> 2.924517e-03,
>>>>> 1.608878e-03,
>>>>> 5.410003e-04,
>>>>> 1.345410e-04,
>>>>> 8.147859e-05,
>>>>> 8.000402e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> 8.000000e-05,
>>>>> &
>>>>>
>>>>> # Elliptic solver parameters
>>>>> &PARM02
>>>>> &
>>>>>
>>>>> # Time stepping parameters
>>>>> &PARM03
>>>>> nIter0=0006205000,
>>>>> # 5000 years
>>>>> nTimeSteps=1825000,
>>>>> deltaTMom=3600,
>>>>> deltaTtracer=86400,
>>>>> abEps=0.1,
>>>>> # write out every 50 years
>>>>> pChkptFreq=1.5768e10,
>>>>> chkptFreq=1.5768e9,
>>>>> dumpFreq=1.5768e9,
>>>>> monitorFreq=1.5768e7,
>>>>> tauThetaClimRelax=764400.,
>>>>> cAdjFreq=0,
>>>>> pickupStrictlyMatch=.FALSE.,
>>>>> &
>>>>>
>>>>> # Gridding parameters
>>>>> &PARM04
>>>>> usingCartesianGrid=.TRUE.,
>>>>> usingSphericalPolarGrid=.FALSE.,
>>>>> dXspacing=80.e3,
>>>>> dYspacing=80.e3,
>>>>> delZ= 12.0505, 14.9159, 18.4328, 22.7337, 27.9692,
>>>>> 34.3067, 41.9245, 51.0025, 61.7057, 74.1598,
>>>>> 88.4181, 104.4189, 121.9376, 140.5412, 159.5568,
>>>>> 178.0710, 194.9769, 209.0770, 219.2372, 224.5642,
>>>>> &
>>>>>
>>>>> # Input datasets
>>>>> &PARM05
>>>>> bathyFile='topo_two.bin',
>>>>> thetaClimFile='TSurf.bin',
>>>>> zonalWin
>>>>
>>>> _______________________________________________
>>>> MITgcm-support mailing list
>>>> MITgcm-support at mitgcm.org
>>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>>
>>> -----------------------------------------------------------
>>> Dr. Christopher L. Wolfe 858-534-4560
>>> Physical Oceanography Research Division OAR 357
>>> Scripps Institution of Oceanography, UCSD clwolfe at ucsd.edu
>>> -----------------------------------------------------------
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>>
>>
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>
>
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--
Jody Klymak
http://web.uvic.ca/~jklymak/
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