[MITgcm-support] Problem with EXF package

Thu Dec 6 13:52:01 EST 2007

Hi there,

if you are using exf,
then the parameters in file "data" under PRM03 related to
>   periodicExternalForcing=.TRUE.,
>   externForcingPeriod=43200., <-- your period
>   externForcingCycle=86400.,  <--- your circle
are ignored.
If they aren't ignored, something unwanted (i.e. wrong) is going on.

Abbas,
a bit hard to figure out your problem.
Quick look at your output says that,
1. you have enabled EXF,
2. exf reads wind speed fields uwind, vwind properly,
    (in your output look for %MON exf_ ... )
3. You are prescribing constant uwind=10 m/s, vwind =0 m/s, right?
    (in your output uwind_min=uwind_max=10)
4. No calculation of ustress, vstress from uwind, vwind takes place,
    which is odd.

One suspicion:
in EXF_OPTIONS.h set
# undef ALLOW_ATM_TEMP
which means you only want to provide atmospheric wind (speeds),
but not atmos. state (atemp, aqh, etc).
There is a subtle
           if ( atemp(i,j,bi,bj) .ne. 0. _d 0 ) then

statement in that block if code expects atmospheric state,
which might be the cause of your problem.

If that doesn't help:
If you're courrageous (which you should be),
have a look at
1. exf_wind.F and see whether cw, sw fields are nonzero,
2. exf_bulkformulae.F whether ustress, vstress are computed proprely.

-Patrick

On Dec 6, 2007, at 12:07 PM, Abbas Dorostkar wrote:

> Hi Van Thinh,
> Thank you for prompt reply.
> I would like to use wind speed as an input data although I can write a
> Matlab routine to convert them to wind stress. Did you use just wind
> speed data?
> Do you mean that I have to use  EXF package in conjunction with  
> external
> forcing through PARM03? If so, You have defined wind stress file at
> PARM03 not wind speed. Right? I am a little confused because I read a
> post from Martin that periodicExternalForcing=.TRUE. flag does not  
> have
> any effect when we use EXF.
> (http://forge.csail.mit.edu/pipermail/mitgcm-support/2005-August/ 
> 003340.
> html)
>
> I would be glad if you clarify more
> Thanks,
> Abbas
>
> **********************************
> -----Original Message-----
> From: mitgcm-support-bounces at mitgcm.org
> [mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Van Thinh  
> Nguyen
> Sent: Wednesday, December 05, 2007 11:05 AM
> To: mitgcm-support at mitgcm.org
> Subject: RE: [MITgcm-support] Problem with EXF package
>
> Hi Abbas,
>
>
> 1) in data at &PARM03 you should add:
> eg.:
>
>   periodicExternalForcing=.TRUE.,
>   externForcingPeriod=43200., <-- your period
>   externForcingCycle=86400.,  <--- your circle
>
> at &PARM05:
>
>   add your windFile generated from matlab
>
> 2) add your windFile in data.exf
>
> I already did the same way for Lake Erie (with stressfile), Leon (your
> advisor) has seen my results.
>
> Good luck,
>
> Vth
>
> *********************************************************
>
> On Wed, 5 Dec 2007, Abbas Dorostkar wrote:
>
>> Hi all,
>>
>> Thanks to Matt and Patrick for replies.
>>
>> I definitely set useEXF = .TRUE. and use data.exf (attached) with the
>> package. The problem is wind speed does not get converted to wind
>> stress.
>>
>> I had a look on previous posts. It seems some other users had this
>> problem before. See post
>>
> http://forge.csail.mit.edu/pipermail/mitgcm-support/2006-November/ 
> 004434
>> .html
>>
>> I have used Cartesian coordinate and specified wind speeds at every
> grid
>> point and at every time point. The file is wind(nx,ny,nt), where  
>> nt is
>> the number of hours I have, like wind(x,y,t1), wind(x,y,t2), and so
> on.
>> I am not sure if the input file I have generated is correct. However,
>> using same Matlab routine to generate wind stress file to be used in
> the
>> file "data", in namelist PARM03, works fine.
>>
>> I have also attached monitor output.
>>
>> I would appreciate it if someone give me ideas.
>>
>> Abbas
>>
>>
>>
>> -----Original Message-----
>> From: mitgcm-support-bounces at mitgcm.org
>> [mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Matthew
> Mazloff
>> Sent: Wednesday, December 05, 2007 1:52 AM
>> To: mitgcm-support at mitgcm.org
>> Subject: Re: [MITgcm-support] Problem with EXF package
>>
>> Hi Abbas,
>>
>> You have to use data.exf with the EXF package.  data simply will not
> do.
>>
>> -Matt
>>
>> e.g.
>> http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm/verification/
>> global1x1_tot/input/data.exf?rev=1.5&content-type=text/vnd.viewcvs-
>> markup
>>
>>
>> On Dec 4, 2007, at 1:01 PM, Abbas Dorostkar wrote:
>>
>>> Hi all,
>>> To see If I can get nonlinear internal waves with my model,  I
>>> considered horizontal isotherms throughout a lake and applied a wind
>>> stress for some hours along the main axis and then turned off the
> wind
>>> suddenly. When I use EXF package to prescribe time dependent wind
>>> forcing (wind speed as an input), It seems model doesn't feel the
> wind
>>> stress. I checked the monitor statistics for that and the values for
>>> wind stress are zero.  However, when I define wind stress in the  
>>> file
>>> "data", in namelist PARM03, everything works fine.
>>> I would prefer to use EXF package as I have wind speed but I am not
>>> sure
>>> what the problem is. Any ideas?
>>> Thank you
>>> Abbas
>>>
>>> *************************
>>> Abbas Dorostkar, PhD Student
>>> Department of Civil Engineering
>>> Queen's University
>>> Room 444, Ellis Hall
>>> 58 University Avenue
>>> Kingston, Ontario, CANADA  K7L 3N6
>>> **********************************
>>>
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>
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---
Patrick Heimbach | heimbach at mit.edu | http://www.mit.edu/~heimbach
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