[MITgcm-support] [EXTERNAL] Can not run a regional model for long time

Sun Sep 18 16:41:10 EDT 2022

Hi Sabri, maybe you have modes of variability that slosh around inside your regional domain, reflect off the open boundaries, and accumulate energy.
My understanding is that Orlanski boundary condition will be free of reflection for a single internal mode only.
Other internal (or shallow water) modes may not be damped.  Adding a sponge layer may help.

All of the above is speculation from someone who does not fully understand how Orlanski boundary conditions work.

Dimitris

On Sep 18, 2022, at 11:55 AM, Sabri MUTLU (MAM-ÇTÜE) <sabri.mutlu at tubitak.gov.tr<mailto:sabri.mutlu at tubitak.gov.tr>> wrote:

Hi Matt,

Max. U velocity at the boundary becomes higher than 1 m/sec, and also the current very close to the boundary reaches unrealistic speeds.
But do not know why, since it happens after 8 days in the simulation.
obc_W_uVel_max value always increases with time. Maybe this is the problem. If it is, how to solve it?

Best.
Sabri

________________________________
Kimden: "Matthew Mazloff" <mmazloff at ucsd.edu<mailto:mmazloff at ucsd.edu>>
Kime: "mitgcm-support" <mitgcm-support at mitgcm.org<mailto:mitgcm-support at mitgcm.org>>
Gönderilenler: 18 Eylül Pazar 2022 19:16:57
Konu: Re: [MITgcm-support] Can not run a regional model for long time

You need to find out why it is becoming unstable. Have a look at the solution and see if you can see where and why it is blowing up.

Matt

On Sep 18, 2022, at 6:08 AM, Sabri MUTLU (MAM-ÇTÜE) <sabri.mutlu at tubitak.gov.tr<mailto:sabri.mutlu at tubitak.gov.tr>> wrote:

Hi all,

As a newbie in this field, I need help for the following problem, which I have been trying to deal with for a long time.

I built a regional model for my thesis study. When I try to run it for 12 or more days, it gives "NaN" values after 8 or 9 days later in the model.
Could you please examine the following model configuration and give me an idea for possible solution?

(I had to choose Orlanski method since don't have any boundary condition to feed the model.)

Thank you in advance.
Sabri

 &PARM01
 viscAh=2.E-2,
 viscAz=1.5E-5,
 no_slip_sides=.TRUE.,
 no_slip_bottom=.TRUE.,
 diffKhT=2.E-2,
 diffKhS=2.E-2,
 diffKzT=2.E-5,
 diffKzS=2.E-5,
 f0=0.948E-4,
 implicitFreeSurface=.TRUE.,
 exactConserv=.TRUE.,
 implicitDiffusion=.TRUE.,
 implicitViscosity=.TRUE.,
 eosType = 'JMD95Z',
 tRef=22.2803,22.3383,22.3646,22.4220,22.5469,22.5081,21.0406,19.6075,18.3619,16.7902,15.8310,15.4016,15.3625,15.3935,15.4334,15.4465,15.4508,15.4710,15.5226,
      15.5428,15.5485,15.5589,15.5829,15.5860,15.5859,15.5767,15.5572,15.5477,15.5357,15.5068,15.4782,15.4640,15.4337,15.3816,15.3480,15.2998,15.2423,15.2127,
      15.1271,15.0639,15.0086,14.9722,14.9229,14.8937,14.8470,14.8073,14.7838,14.7677,14.7392,14.7210,14.7037,14.7036,14.7035,14.7034,14.7033,
 sRef=24.3775,24.4042,24.4730,24.5782,24.7042,24.8407,25.8279,26.4026,28.0163,30.1542,31.7531,33.9951,37.0132,37.5629,37.8303,37.9592,38.0011,38.1433,38.2744,
      38.3184,38.3548,38.4269,38.5535,38.6043,38.6738,38.7411,38.7479,38.7496,38.7510,38.7512,38.7469,38.7529,38.7569,38.7644,38.7666,38.7683,38.7698,38.7696,
      38.7635,38.7563,38.7513,38.7476,38.7427,38.7399,38.7354,38.7326,38.7305,38.7280,38.7254,38.7236,38.7220,38.7220,38.7220,38.7220,38.7220,
 staggerTimeStep = .TRUE.,
 tempAdvScheme = 33,
 saltAdvScheme = 33,
 useSingleCpuIO=.TRUE.,
 bottomDragQuadratic = 0.02,
 select_rStar = 0,
 &

 &PARM02
 cg2dMaxIters=300,
 cg2dTargetResidual=1.E-13,
 cg3dMaxIters=20,
 cg3dTargetResidual=1.E-8,
 &
---------
 &PARM03
 startTime  = 0.,
 endTime = 1036800.,
 deltaT=5,
 dumpFreq=10800.,
 monitorFreq=3600.,
 monitorSelect=2,
 periodicExternalForcing=.TRUE.,
 externForcingPeriod=10800.,
 externForcingCycle=1036800.,
 &

 &PARM04
 usingSphericalPolarGrid=.TRUE.,
 delz = 32*2,22*8,10,
 delX = 528*0.0013,
 delY = 164*0.001,
 ygOrigin=40.656,
 xgOrigin=29.2612,
 &

 &PARM05
 bathyFile='bathy_v6_528-164.bin',
 zonalWindFile='windU_2309-0510.bin',
 meridWindFile='windV_2309-0510.bin',
 &

# Open-boundaries
 &OBCS_PARM01
 OB_Iwest=164*1,
 useOrlanskiWest=.TRUE.,
 useOBCSbalance=.TRUE.,
 useOBCSsponge=.FALSE.,
 OBCS_balanceFacW = -1.,
 &

# Packages
 &PACKAGES
 useOBCS=.TRUE.,
 useKPP =.TRUE.,
 &

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