[MITgcm-support] time continuous source for ptracers: how to use ptracers_forcing_surf.F

[Camille Mazoyer]

Hi all,

Thanks Martin for your answer. I tried to use ptracers_forcing_surf.F 
but I didn't manage to make it work: anyway, using rbcs may be more 
flexible. So I'm trying to understand it.

So I would like to use RBCS package for one tracer, and I would like to 
have a continuous source at (i=25, j=80, k=1) for a value of 100.0 
units, for example. I have several questions with rbcs.

my data.rbcs is:

&RBCS_PARM01
relaxMaskFile(3) = 'ptracers_mask.bin',
rbcsForcingPeriod = 0.,
useRBCtemp = .FALSE.,
useRBCsalt = .FALSE.,
/

&RBCS_PARM02
useRBCptrnum(1)=.TRUE.,
tauRelaxPTR(1) = 3600.,
relaxPtracerFile(1) = 'ptracers.bin',
/

and my data.ptracers is:

  &PTRACERS_PARM01
  PTRACERS_numInUse=1,
  PTRACERS_Iter0= 0000141840,
  PTRACERS_taveFreq=60.0,
# tracer 1
  PTRACERS_names(1)='PT',
  PTRACERS_long_names(1)='Passive tracer',
  PTRACERS_units(1)='no units',
  PTRACERS_advScheme(1)=77,
  PTRACERS_useKPP(1)=.TRUE. ,
  PTRACERS_initialFile(1)='ptracers.bin',
  &

  Here are my questions:

1) I don't understand very well how to choose tauRelaxPTR values. My dt 
time step is 10s, and if I use tauRelaxPTR=10.0 s (for continuous 
source), my run explodes. I see that my run doesn't explode when 
tauRelaxPTR is from around 3600.0 seconds, but at this value, the 
continuous source (i=25,j=80,k=1) is around 90.0 after 1 hour, whereas 
in my relaxPtracerFile I wanted a value of 100 at this point. (see 
attach file). I thought that tauRelaxPTR was the timelapse to reach the 
value written in relaxPtracerFile ? How to do to reach 100 units more 
precisely in my source cell?

2) I would like to know your advices for the choice of the mask matrix 
in ptracers_mask.bin. For my test, I choose a mask value of exp( −0.8x), 
with x the distance to my source cell (i=25,j=80,k=1). I was inspired by 
this pdf, see page 92/160: 
http://digitool.library.mcgill.ca/R/?func=dbin-jump-full&object_id=132855&local_base=GEN01-MCG02

3) Just to know: ptracers.bin contained a matrix of 0 everywhere except 
a value of 100 units in my source cell (i=25,j=80,k=1). Can we have a 
continuous source for only one cell?

Thank you very much for your advices,

Camille



Le 10/10/2017 à 13:13, Martin Losch a écrit :
> Hi Camille,
>
> to compute global indices from local i,j,bi,bj you can do this (where ig,jg are now the global indices):
>
>            jg = myYGlobalLo-1+(bj-1)*sNy+j
>            ig = myXGlobalLo-1+(bi-1)*sNx+i
>
> I “stole” this from pkg/cost/cost_test.F, where this is also used to find global indices where the “cost function” is evaluated.
>
> Martin
>
>
>> On 10. Oct 2017, at 11:20, Camille Mazoyer<mazoyer at univ-tln.fr>  wrote:
>>
>> Dear all,
>>
>> I'm starting to work with ptracers to study passive tracers circulation in a mid closed bay. I'm starting to have nice results with it. Until now, I put an initial concentration at time t0, and then, I observe where the tracers go.
>>
>> Now, I would like to add a time continuous source. I saw on the mailing list that there are two ways of doing this:
>>
>> 1)- with rbcs package
>>
>> 2) - modifying  ptracers_forcing_surf.F source code.
>>
>> I tryed option 1 but I did'nt manage to do what I want. I think option 2 is easier (?) for starting?
>>
>> => so option 2:  I see where to modify the ptracers_forcing_surf.F code (see below), but I have a question about local i,j and global i,j. I want to add a source at i=22:23, j=84:85, k=1 (surface). These are global indices. How can I know which tile, and what local indices I have to write? (because the code what local indices no?)
>>
>> C Example of how to add forcing at the surface
>>        DO iTrc=1,PTRACERS_numInUse
>> c       IF ( PTRACERS_StepFwd(iTrc) ) THEN
>>            DO j = jMin, jMax
>>             DO i = iMin, iMax
>> c             surfaceForcingPTr(i,j,bi,bj,iTrc) = 0. _d 0
>>               surfaceForcingPTr(i,j,bi,bj,iTrc) = 0. _d 0
>> c    &                        + surfaceForcingS(i,j,bi,bj)
>>             ENDDO
>>            ENDDO
>> c       ENDIF
>>        ENDDO
>>
>>
>> Thanks you very much for your help,
>>
>> Have a good day,
>>
>> Camille
>>
>> -- 
>> ------------------------------------------
>> Camille Mazoyer
>> Phd Student
>> Mediterranean Institute of Oceanology (MIO)
>> Institut de Mathématiques de Toulon (IMATH)
>> Université de TOULON
>> Bat X - CS 60584
>> 83041 TOULON cedex 9
>> France
>> tel: +33.4.94.14.24.50
>> Email:mazoyer at univ-tln.fr
>> http://mio.pytheas.univ-amu.fr/
>> http://imath.fr/
>>
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-- 
------------------------------------------
Camille Mazoyer
Phd Student
Mediterranean Institute of Oceanology (MIO)
Institut de Mathématiques de Toulon (IMATH)
Université de TOULON
Bat X - CS 60584
83041 TOULON cedex 9
France
tel: +33.4.94.14.24.50
Email:mazoyer at univ-tln.fr
http://mio.pytheas.univ-amu.fr/
http://imath.fr/

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