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

[Chris Hill]

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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