[MITgcm-support] more KPP blues, maybe related?

Mon Oct 27 09:02:33 EST 2003

Great, glad it was in your own bit!!! 

I will check with Benjamin what EOS he is using too just in case his
problems are related.

Chris

> -----Original Message-----
> From: mitgcm-support-bounces at mitgcm.org
> [mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Martin Losch
> Sent: Monday, October 27, 2003 8:26 AM
> To: mitgcm-support at mitgcm.org
> Subject: Re: [MITgcm-support] more KPP blues, maybe related?
> 
> 
> Chris,
> 
> I was about to write an email. I think I have localized the problem,
> but I haven't fixed it. It doesn't have anything to do with KPP but 
> with the equation of state. And as usual, I am to blame for all the 
> trouble:
> The problem only occurs with I use
> eosType='MDJWF',
> so the super-duper new, latest, fantastic EOS by McDougall et al. 
> (2003), but it's not the equation of state itself but probably alpha 
> (in find_alpha), that's wrong. And since find_alpha/beta is 
> only called 
> from somewhere within kpp_routines.F and nobody ever uses MDJWF 
> together with KPP (probably nobody every uses MDJWF to begin with, 
> there's no test case for it), nobody has ever had the problem. I am 
> glad that I am only responsible for my loss of time.
> 
> I'll try to fix the problem (it's probably just a wrong
> coefficient or 
> so) and then you can decide when or if I can check it in.
> 
> Martin
> 
> On Monday, October 27, 2003, at 02:15  PM, Chris Hill wrote:
> 
> > Martin,
> >
> >  Could you put your setup on-line at MIT (if its not already there)
> > somewhere? There are a couple of other coarse resolution KPP issues 
> > that people have found here (though not of the 30-40 day blow up 
> > sort). It would be good to get Dimitris to take a quick look at the 
> > various setups
> > people have while he is here this week.
> >
> > Thanks,
> >
> > Chris
> >
> >
> >
> >> -----Original Message-----
> >> From: mitgcm-support-bounces at mitgcm.org
> >> [mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of 
> Martin Losch
> >> Sent: Monday, October 27, 2003 3:29 AM
> >> To: mitgcm-support at mitgcm.org
> >> Subject: Re: [MITgcm-support] more KPP blues, maybe related?
> >>
> >>
> >> Hi again,
> >>
> >> I have made this mistake with the downward solar radiation, but
> >> unfortunately, this does not appear to be my real problem. 
> I checked
> >> my input fields again, and I had another look at FFIELDS.h where I
> >> had already appreciated the ranges provided. I use net shortwave
> >> radiation
> >> (netsw) now. My fields are all in the proper ranges: (with Qnet =
> >> latent+sensible+netlw+netsw, that's the default for
> >> global_ocean.90x40x15, Qsw=netsw)
> >> -225 < Qnet < 442, FFIELDS.h says: Typical range: -250 <
> Qnet < 600
> >> -321 < Qsw < 0, FFIELDS.h says: Typical range: -350 < Qsw < 0 and
> >> here may be the problem: -9 < Qnet-Qsw < 550 which I think 
> is what I
> >> should use for surfQFile together with surfQswFile
> >>
> >> As far as I understand, I can use either
> >> surfQFile = Qnet
> >> or
> >> surfQFile = Qnet-Qsw
> >> surfQswFile = Qsw
> >> I actually tried the combination
> >> surfQfile = Qnet
> >> surfQswFile = Qsw
> >> which doesn't make any sense to me because netsw is
> included twice.
> >> But only when I use surfQFile = Qnet alone (without surfQswFile) 
> >> the model remains stable. The other two combinations above with KPP
> >> blow up after
> >> 30-45 days. It must be something really stupid, like a scale
> >> factor of
> >> 1000 somewhere, because the effect is so drastic.
> >>
> >> Also, when I turn off KPP in data.pkg, then the model
> appears to be
> >> stable with surfQFile=Qnet-Qsw; surfQswFile=Qsw;
> >>
> >> I am still hoping for a miracle.
> >>
> >> Martin
> >>
> >>
> >> On Sunday, October 26, 2003, at 05:28  PM, Dimitris
> Menemenlis wrote:
> >>
> >>>>> For SHORT_WAVE_HEATING input "Qsw" I use downward solar
> >> flux (with
> >>>>> oposite sign) which may be wrong (now I am almost sure
> >> it's wrong).
> >>>
> >>> Martin, if you are using a relatively recent version of the
> >> code, have
> >>> a
> >>> look at definitions at beginning of FFIELDS.h (or
> >> exf_fields.h if you
> >>> are using pkg/exf).  For each input field there is a
> >> typical range of
> >>> values.
> >>>
> >>> For global_ocean.90x40x15 experiment you need to use "net
> shortwave
> >>> radiation", which is different from "downward shortwave
> radiation",
> >>> and which is provided separately by NCEP.
> >>>
> >>> Note that if you are using pkg/exf, then you can specify
> either net
> >>> (swflux) or downward (swdown) shortwave radiation, and the
> >> model will
> >>> convert as needed:
> >>>
> >>> c--   Compute net from downward and downward from net longwave and
> >>> c     shortwave radiation, if needed.
> >>> c     lwflux = Stefan-Boltzman constant * emissivity * 
> SST - lwdown
> >>> c     swflux = - ( 1 - albedo ) * swdown
> >>>
> >>> Hope this helps.
> >>>
> >>> One last thing, there is a small but finite chance that sign
> >>> convention for Qnet and Qsw may change for release 2.  So
> >> make sure to
> >>> take a look at FFIELDS.h and at exf_fields.h when you
> >> download release
> >>> 2.
> >>>
> >>> D.
> >>>
> >>> --
> >>> 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
> >>>
> >>> _______________________________________________
> >>> MITgcm-support mailing list
> >>> MITgcm-support at mitgcm.org
> >>> http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
> >>
> >> _______________________________________________
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> >
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