[MITgcm-support] Re : Query regarding "exf package".

Martin Losch Martin.Losch at awi.de
Fri Jan 13 09:59:23 EST 2012 

Hi Himansu,

I think I found the problem: the exf-package had the wrong CPP-flags. You only want to force your model with windstress, but you had  ALLOW_ATM_TEMP and ALLOW_DOWNWARD_RADIATION defined. With these flags, the model expects other atmospheric forcing fields (air temperature, humidity, downwelling radiation, etc.) to compute heat and freshwater fluxes from bulkformulae. Since you don't give it any values it assumes atemp=0 (in Kelvin!), aqh=0, etc. giving you weird heat fluxes. You set useExfCheckRange=.FALSE., so that the erroneous heat fluxes were not caught by the model.
When you unset the above flags in EXF_OPTIONS.h you get the same results in both of your experiments.
#
I only ran the model for 8640 timesteps, but I can further confirm that
1. the windstress is read in properly
2. the windstress is not exactly the same between the runs: it appears to be masked along the boundaries in one case (the exf-case) but not in the other one, but that should not be a problem, as the masked values are over (u,v)-land points anyway.

It may also help to create initial conditions (via extraploation) that have non-zero value in your entire domain (and remove the  checkIniTemp=.false., checkIniSalt=.false., flags that mask this problem). I am getting this with your configuration:
** WARNINGS ** INI_THETA: found        32 wet grid-pts with theta=0 identically.
** WARNINGS ** INI_SALT: found      3999 wet grid-pts with salt=0 identically.
That's probably not very good, because it lead to strong adjustment processes during the spin-up.

I also noticed that you make your model very viscous. I recommend using a better advection scheme, e.g. 33 ( with staggerTimeStep=.true.) and reducing or even removing the horizontal diffusivity. The horizontal viscosity is also very high. Try viscAhGrid = 0.1, (see the documentation for more details on advection schemes and setting the viscosity).

Martin

On Jan 13, 2012, at 1:54 PM, himansu pradhan wrote:

> Hi Sir, 
>  Thank you for offering me this opportunity . This will definitly help me.
> The link to the experiments (experiments.tar.gz) is here :
> 
> http://www.4shared.com/archive/NSDlcGGW/experimentstar.html
> 
> To note further :
> 
> (a) i am using, MITgcmUV version:  checkpoint63c.
> 
> (b) The attached experiments are : 
> 
> exp1d   : In "data" file u/v wind stress files are used.
> 
> exp1de : In "data.exf: files u/v wind stress files are used. 
> 
> (c) The input(bathyfile, temperature , salinity and the wind stress files) to both the experiments are SAME.
> 
> I hope i have given the complete setup. 
> 
> Thank you .
> 
> Himansu Kesari Pradhan
> India.
> 
> On Thu, Jan 12, 2012 at 2:57 PM, Martin Losch <Martin.Losch at awi.de> wrote:
> Himansu,
> 
> I do not see any obvious mistakes in your files. I can offer to do the following: Provide your complete set-up, that is, the "code" directory and the "input" directory (so all data*, files initial conditions, if you think that they are necessary and forcing fields), and I'll try to reproduce your problem.
> 
> BUT, don't send this to this list (your previous post was again pretty large). Put it somewhere to download.
> 
> Martin
> 
> On Jan 12, 2012, at 6:11 AM, himansu pradhan wrote:
> 
> > Hi Sir,
> >
> > I am sorry for sending large files and figures of *.fig extension. I will take care regarding this from the next posts.
> >
> > I have attached TWO experiments.
> >
> > exp1d   : In "data" file u/v wind stress files are used.
> >
> > exp1de : In "data.exf: files u/v wind stress files are used.
> >
> >  Both these experiments uses the same bathyfile, temperature , salinity and the wind stress files. The results of these experiments are in their respective folders.
> >
> > Thank you
> >
> > Himansu Kesari Pradhan
> > India
> >
> > On Tue, Jan 10, 2012 at 7:43 PM, Martin Losch <Martin.Losch at awi.de> wrote:
> > Himansu,
> >
> > 1. please do not send large files to this list, rather post them somewhere and send the link.
> > 2. I cannot read *.fig files
> > 3. Your jpg-plots look like the surface forcing you specify does not make sense. Check (in both experiments) that the model sees the correct forcing, e.g. by writing the appropriate diagnostics with the diagnostics-package (oceTAUX and oceTAUY).
> >
> > Please send your entire data and data.exf and data.cal files, as you use them in your experiments. From you previous emails it was not clear to me, what you are actually specifying.
> >
> > M.
> >
> > On Jan 10, 2012, at 8:18 AM, himansu pradhan wrote:
> >
> > > Hi Matrin Sir,
> > >
> > > Thanks for the reply.......
> > > your suggestation worked.... (both : setting the timeperiod and stress on C grid)
> > >
> > > # ********data.exf*************
> > > # External Forcing Data
> > > # *********************
> > >  &EXF_NML_01
> > >  exf_iprec         = 64,
> > > #exf_verbose       = .TRUE.,
> > >  readstressOnCgrid=.TRUE.,
> > >  useExfCheckRange=.FALSE.,
> > >  &
> > >  &EXF_NML_02
> > >  ustressstartdate1=20110101,
> > >  ustressstartdate2=000000,
> > >  ustressperiod=0,
> > > #
> > >  vstressstartdate1=20110101,
> > >  vstressstartdate2=000000,
> > >  vstressperiod=0,
> > > #
> > >  ustressfile  = 'May23Ustr.bin',
> > >  vstressfile  = 'May23Vstr.bin',
> > > [.......]
> > >
> > > ........but........ ?????
> > > the result (plot) for this run (i.e. for "current","temperature" , salinity ) are not fine...?????.... the figures attached can give a clear look at that.........
> > >
> > > The results of the model run where u/v- windstress files are used in "data.exf" are in  Figure (a) and (b). The plot for vectors seems more distorted ( donot know why...???????........).
> > >
> > > (a) Current_dataexf.fig
> > > (b) temp_dataexf.jpg
> > >
> > > The results of the model run where windstress files are used in "data" are Figure (c) and (d). This results are FINE.....(This is what i wish to get whn using u/v-windstress files in "data.exf")
> > > (c)   Current_data.fig
> > > (d) temp_data.jpg
> > >
> > >
> > > Any suggestations
> > >
> > > Thank you,
> > >
> > > Himansu Kesari Pradhan
> > > India
> > >
> > >
> > > On Mon, Jan 9, 2012 at 2:27 PM, Martin Losch <Martin.Losch at awi.de> wrote:
> > > Himansu,
> > >
> > > for constant wind stress (one time slice) you need to have u/vtressperiod = 0. (which is the default if you do not specify anything) in data.exf, otherwise the model is trying to read the next field at t=t0+u/vstressperiod.
> > >
> > > Further, readstressOnAgrid=.TRUE., makes the model believe that the stress components are defined on the center points of the C-grid (I think), so that they are interpolated to the U/V points. Specifying
> > >  zonalWindFile='pUstress.bin',
> > >  meridWindFile='pVstress.bin',
> > > in data&PARM05 assumes stress at U/V points automatically. Set readStressOnCgrid = .true., if you want to do the same in with pkg/exf.
> > >
> > > Martin
> > > On Jan 9, 2012, at 7:57 AM, himansu pradhan wrote:
> > >
> > > > hi MITgcm users,
> > > >
> > > > A doubt to clarify
> > > >
> > > > My u/v-windstress file is of one time slice (157 * 133) . This is what i was using in "data" file .
> > > > *******data******
> > > >  &PARM03
> > > >  startTime=0,
> > > >  endTime=864000,
> > > >  deltaT=10.0,
> > > >  abEps=0.1,
> > > > # momDissip_In_AB=.FALSE.,
> > > >  pChkptFreq=432000,
> > > > # chkptFreq=432000,
> > > >  dumpFreq=21600,
> > > >  &
> > > > # Input datasets
> > > >  &PARM05
> > > >  bathyFile='top_MOD.bin',
> > > >  hydrogThetaFile='15lvlT_may.bin',
> > > >  hydrogSaltFile='15lvlS_may.bin',
> > > > # zonalWindFile='pUstress.bin',
> > > > # meridWindFile='pVstress.bin',
> > > > &
> > > > but when i use the SAME u/v- windstress file (157*133) in "data.exf" . The model didnot run ..!!!!!!!!
> > > > # *********data.exf************
> > > > # External Forcing Data
> > > > # *********************
> > > >  &EXF_NML_01
> > > >  exf_iprec         = 64,
> > > >  readstressOnAgrid=.TRUE.,
> > > >  useExfCheckRange=.FALSE.,
> > > >  &
> > > >  &EXF_NML_02
> > > >  ustressstartdate1=20110101,
> > > >  ustressstartdate2=000000,
> > > >  ustressperiod=864000,
> > > > #
> > > >  vstressstartdate1=20110101,
> > > >  vstressstartdate2=000000,
> > > >  vstressperiod=864000,
> > > > #
> > > >  ustressfile  = 'pUstress.bin',
> > > >  vstressfile  = 'pVstress.bin',
> > > >  &
> > > > [....]
> > > >
> > > > finally,
> > > > i created u/v- windstress file having 2 time slabs (i.e. 157*133*2)............ The model "runs" SUCESSFULLY for the total period of intergration. .
> > > >
> > > > my doubt is :
> > > >
> > > > (a) why i need to give 2 time slabs (157*133*2)  in "data.exf".....??? (whereas, In "data" i use only one time slab(157*133) for the complete period of integration)
> > > >
> > > > Am i doing right here  ???
> > > >
> > > >
> > > > Thank you ,
> > > >
> > > > Himansu Kesari Pradhan,
> > > > India.
> > > > _______________________________________________
> > > > MITgcm-support mailing list
> > > > MITgcm-support at mitgcm.org
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> > >
> > >
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> > >
> > > <Current_dataexf.fig><Current_data.fig><temp_dataexf.jpg><temp_data.jpg>_______________________________________________
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