[MITgcm-support] synchronous vs asynchronous integrations
David Wang
dwang at ldeo.columbia.edu
Fri Jun 2 14:31:32 EDT 2006
Hi Samar,
Thanks for pointing this out to me. I think this is the thread that you
mentioned:
http://mitgcm.org/pipermail/mitgcm-support/2005-January/002816.html
to be clearer, I need a quasi-equilibrium of the upper ocean, instead of
a full equilibrium which would take much longer time. If the strategy
that Martin suggested is implemented, when should I switch from
asychronous mode to sychronous mode (i.e., how to know "the T/S-drift
has become negligible" technically?); or, just safely stay with
synchronous runs?
Thx, -d.
Samar Khatiwala wrote:
> David
>
> Not sure why you expect the two to give similar results, especially
> with seasonal forcing.
> (See papers by Danabasoglu and Danabasoglu & McWilliams.)
> My experience is that the extent to which they differ is (at the very
> least) a function of the
> resolution, advection scheme, and the ratio of tracer to momentum time
> steps. Of course,
> you should only be comparing the final equilibrium solutions, and not
> some intermediate
> transient solution. I take it you haven't run it long enough to spin up
> your model to equilibrium.
> There is a long exchange on this topic between myself and Martin Losch
> on the mitgcm-support
> list.
>
> Samar
>
> On Jun 2, 2006, at 11:40 AM, David Wang wrote:
>
>> Hello,
>>
>> I ran two model runs with the same configuration, the same initial
>> fields and the same surface forcing fields, but different timesteps
>> (one is sychronous: deltaT = 3600s; another is asynchronous:
>> deltaTmom = 900s, deltaTtracer = deltrTClock = 10800s). They give
>> considerably different results, which is not what I expected. Of
>> course I prefer the asychronous one since it takes much less
>> integration time, but the differences make me to doubt the integrity
>> of these runs.
>>
>> The model domain is the tropical pacific. The initial fields are
>> climatological potential temp and salinity. The model is forced by
>> climatological monthly forcings. kpp, gmredi, rbcs packages are used.
>>
>> I'm attaching my data namelist file and a plot of momKE_ave
>> timeseries over the first model year (which is to show how different
>> they are. blue is the sychronous run and red is the asychronous run).
>> The temperature field snapshots at the end of the first model year
>> also differ, esp. near the equator.
>>
>> If anyone would have any ideas on what might go wrong, plz let me
>> know. Thanks very much.
>>
>> - d.
>> # ====================
>> # | Model parameters |
>> # ====================
>> #
>> # Continuous equation parameters
>> &PARM01
>> tRef = 25.95, 25.85, 25.70, 25.41, 25.02,
>> 24.56, 24.00, 23.45, 22.84, 22.23,
>> 21.61, 20.99, 20.38, 19.77, 19.17,
>> 18.56, 17.86, 16.91, 15.74, 14.44,
>> 13.09, 11.74, 10.27, 8.90, 7.64,
>> 6.61, 5.82, 5.18, 4.63, 4.21,
>> 3.84, 3.51, 3.22, 2.91, 2.59,
>> 2.24, 1.95, 1.71, 1.54, 1.36,
>> 1.22, 1.10, 1.02, 0.95, 0.92,
>> #
>> sRef = 45*35.,
>> #
>> viscA4 = 1.E13,
>> viscAz = 1.E-4,
>> diffKhT = 0.E3,
>> diffKzT = 5.E-6,
>> diffKhS = 0.E3,
>> diffKzS = 5.E-6,
>> #
>> rhoNil = 1025.,
>> gravity = 9.81,
>> eosType = 'LINEAR',
>> tAlpha = 2.E-4,
>> sBeta = 7.4E-4,
>> #
>> rigidLid = .FALSE.,
>> implicitFreeSurface = .TRUE.,
>> no_slip_bottom = .TRUE.,
>> no_slip_sides = .TRUE.,
>> #
>> # ivdc_kappa=10.,
>> implicitDiffusion=.TRUE.,
>> implicitViscosity=.TRUE.,
>> #
>> # turn on looped cells
>> hFacMin=0.05,
>> readBinaryPrec=32,
>> #
>> &
>>
>> # Elliptic solver parameters
>> &PARM02
>> cg2dMaxIters=1000,
>> cg2dTargetResidual=1.E-13,
>> &
>>
>> # Time stepping parameters
>> &PARM03
>> #
>> startTime = 0.,
>> endTime = 31104000.,
>> #
>> deltaT = 3600.,
>> # deltaTmom = 900.,
>> # deltaTtracer = 10800.,
>> # deltaTClock = 10800.,
>> #
>> abEps = 0.1,
>> pChkptFreq = 0.,
>> chkptFreq = 0.,
>> monitorFreq = 86400.,
>> dumpFreq = 0.,
>> dumpInitAndLast = .TRUE.,
>> #
>> # cAdjFreq = -1.,
>> #
>> # 1 months restoring timescale for surface temperature
>> # 2 months restoring timescale for surface salinity
>> #
>> tauSaltClimRelax = 5184000.,
>> tauThetaClimRelax = 2592000.,
>> periodicExternalForcing = .TRUE.,
>> externForcingPeriod = 2592000.,
>> externForcingCycle = 31104000.,
>> &
>>
>> # Gridding parameters
>> &PARM04
>> usingCartesianGrid = .FALSE.,
>> usingSphericalPolarGrid = .TRUE.,
>> #
>> delX = 160*1.,
>> #
>> delY = 1.0000000, 1.0000000, 1.0000000, 0.9998741,
>> 0.9956741, 0.9835052, 0.9675407, 0.9441032, 0.9175377,
>> 0.8843880, 0.8491249, 0.8084641, 0.7670174, 0.7215805,
>> 0.6768684, 0.6297283, 0.5849037, 0.5392418, 0.4974575,
>> 0.4563580, 0.4205704, 0.3867931, 0.3595371, 0.3353481,
>> 0.3185692, 0.3055687, 0.3004913, 0.2995090, 0.3004913,
>> 0.2995071, 0.3004932, 0.2995071, 0.3004932, 0.2995071,
>> 0.3004913, 0.2995090, 0.3004913, 0.2995090, 0.3004904,
>> 0.2995100, 0.3004894, 0.2995110, 0.3004894, 0.2995100,
>> 0.3004904, 0.2995090, 0.3004913, 0.2995090, 0.3004904,
>> 0.2995100, 0.3004899, 0.2995100, 0.3004899, 0.2995100,
>> 0.3004904, 0.2995095, 0.3004904, 0.2995095, 0.3004906,
>> 0.2995093, 0.3004907, 0.2995093, 0.3004907, 0.2995093,
>> 0.3004906, 0.2995095, 0.3004904, 0.2995095, 0.3004904,
>> 0.2995100, 0.3004899, 0.2995100, 0.3004899, 0.2995100,
>> 0.3004904, 0.2995090, 0.3004913, 0.2995090, 0.3004904,
>> 0.2995100, 0.3004894, 0.2995110, 0.3004894, 0.2995100,
>> 0.3004904, 0.2995090, 0.3004913, 0.2995090, 0.3004913,
>> 0.2995071, 0.3004932, 0.2995071, 0.3004932, 0.2995071,
>> 0.3004913, 0.2995090, 0.3004913, 0.3055687, 0.3185692,
>> 0.3353481, 0.3595371, 0.3867931, 0.4205704, 0.4563580,
>> 0.4974575, 0.5392418, 0.5849037, 0.6297283, 0.6768684,
>> 0.7215805, 0.7670174, 0.8084641, 0.8491249, 0.8843880,
>> 0.9175377, 0.9441032, 0.9675407, 0.9835052, 0.9956741,
>> 0.9998741, 1.0000000, 1.0000000, 1.0000000, 1.0000000,
>> #
>> delZ = 10.00, 10.00, 10.00, 10.00, 10.00,
>> 10.00, 10.00, 10.00, 10.00, 10.00,
>> 10.00, 10.00, 10.00, 10.00, 10.00,
>> 11.13, 14.46, 19.82, 26.94, 35.48,
>> 44.99, 55.00, 65.01, 74.52, 83.06,
>> 90.18, 95.54, 98.87, 100.00, 100.00,
>> 100.00, 100.00, 111.42, 143.93, 192.60,
>> 250.00, 307.40, 356.07, 388.58, 400.00,
>> 400.00, 400.00, 400.00, 400.00, 400.00,
>> #
>> phiMin = -29.,
>> thetaMin = 130.,
>> &
>>
>> # Input datasets
>> &PARM05
>> bathyFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> bathymetry.bin',
>> hydrogThetaFile='/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> woa01_init_theta.bin',
>> hydrogSaltFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> woa01_init_salt.bin',
>> zonalWindFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> dasilva94_monthly_taux.bin',
>> meridWindFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> dasilva94_monthly_tauy.bin',
>> thetaClimFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> woa01_monthly_sst.bin',
>> saltClimFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> woa01_monthly_sss.bin',
>> surfQnetFile= '/data1/fats/dwang/myexps/trop_pacific/input/1x3rd/
>> dasilva94_monthly_qnet0.bin',
>> the_run_name= 'trop_pacific.160x124x45',
>> #
>> &
>> <momKE.png>
>> _______________________________________________
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>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
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