[MITgcm-support] ptracers help/manual

[Manfredi Manizza]

Hi Christopher,

I hope I rightly understood what you need.

I guess you want to use an input file of a assive tracer where you set a
value you pick and you want to keep it fixed in time for the whole 
simulation as a constant source of tracer that you want to follow 
as advected and diffused by the circulation fields.

IF this IS the case you need to have :

File # 1 - An input file corresponding to your tracer source X by Y (your 
domain) with values you set that could be the same everywhere or what is more appropriate for 
your purpose like a source only in a fraction of the domain. Let's call it 
FILE_TRC.bin

File # 2 - A correpsoning file with same dimension where in the position 
(i,j) of your domain you put 1 if you want to have a constant source or 0 if you do not.
Let's call it RESTORE_FILE.bin

File # 3 - IF you run a regional domain you would need a "sponge layer" at 
the boundaries in order to prevent that what goes outside enters back from 
the other side. Let's call RELAX_FILE.bin

To generate this third file you need to set the value all around the 
boundary equal to 1 and apply an exponential fuction that sets the 
value of decay of the tracer that is maximum at the boundary (1)
and then decreases as soon as you move inside your domain.

If this third point is not clear, I can send you the matlab script that 
does that so you can adjust it to your domain.

So then, once you have the files ready, you follow this below :

In the "data.ptracers" (in the run direcory) file, you MUST have :

&PTRACERS_PARM01
  PTRACERS_numInUse=1,
  PTRACERS_Iter0= 0,
#
# The following option is now obsolete:
#  PTRACERS_write_mnc=.TRUE.,
#
# tracer 1 -
  PTRACERS_names(1)='trc1',
  PTRACERS_long_names(1)='trc1',
  PTRACERS_units(1)='mol/m^3',
  PTRACERS_advScheme(1)=77,
  PTRACERS_diffKh(1)=0.E3,
  PTRACERS_diffKr(1)=1.E-5,
  PTRACERS_useGMRedi(1)=.FALSE. ,
  PTRACERS_useKPP(1)=.FALSE. ,
  PTRACERS_initialFile(1)='FILE_TRC.BIN',
  &

In your "data.rbcs" (in the run directory) you MUST have :
# Relax Boundary Conditions parameters
  &RBCS_PARM01
  tauRelaxT = 0.,
  tauRelaxS = 0.,
  relaxMaskFile(1) = ' ',
  relaxMaskFile(2) = ' ',
  relaxMaskFile(3) = 'RELAX_FILE.bin',
  relaxTFile = ' ',
  relaxSFile = ' ',
  rbcsIniter = 0,
  rbcsForcingPeriod = 15552000.,
  rbcsForcingCycle = 0.,
  useRBCtemp = .FALSE.,
  useRBCsalt = .FALSE.,
  useRBCptracers = .TRUE.,
  &end

  &RBCS_PARM02
  useRBCptrnum(1)=.TRUE.
  tauRelaxPTR(1) = 1200.,
  relaxPtracerFile(1) = 'RESTORE_FILE.bin',
  &end

In this way you should be able to not to touch the code
for your experiments just changing those input files
should be enough.

I guess this should work as it has been working for my regional Artcic 
Ocean regional set-up if I understood what you needed.

Cheers
Manfredi





On Mon, 21 May 2007, Christopher L. Wolfe wrote:

>
> Hello modelers,
>
> Does anyone know if there is any documentation for the ptracers package? All 
> I can find in the manual is the offline tutorial and a few comments in the 
> package source, but that's not totally helpful. The tutorial shows how to set 
> up ptracers as an initial value problem, but I want to use it as a boundary 
> value problem. Specifically, I want to fix the surface distribution of the 
> tracers and see how the surface values are transported through the model. Is 
> this possible with the ptracers package? If so, how does one do it?
>
> Thanks,
> Christopher
>
> -----------------------------------------------------------
> Dr. Christopher L. Wolfe             		 858-534-4560
> Physical Oceanography Research Division    OAR 357
> Scripps Institution of Oceanography, UCSD  clwolfe at ucsd.edu
> -----------------------------------------------------------
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
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>

-- 


Manfredi Manizza
Postdoctoral Associate
Room 54-1423
Dept. of Earth, Atmospheric
and Planetary Sciences
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge, MA 02139-4307, USA
phone: 617-452-2977
fax  : 617-253-4464
email: mmanizza at ocean.mit.edu