[MITgcm-support] Re: OB*file interpolation

[Riema Rachmayani]

  I may have been a little sloppy in describing exp4: The open boundary 
files actually contain two time slabs (for testing), but because in 
data periodicExternalForcing is not set to true, time independent 
forcing (and open boundaries) are assumed by default and only the 
first time slab is used.
==> i understand...
  
OK, but in your case you want to prescribe hourly values for 19 days, 
that is 24*19=456 time slabs, so you field must have the size (Nx,Nr, 
456) for a southern or northern boundary and (Ny,Nr,456) for an 
eastern or western boundary (Nr=Nz=number of vertical points).
  ==> (Nx, Nr, 456) for example Nx=111, Nr=8 means i write in a file : 111 different values to the right side, 8 different values downward (8 layers) for each different slab, so there will contains 111*8*456 =404928 values of data??
   
   (Ny, Nr, 456) ,Ny=255,Nr=8,means i write in a file : 255 different values to the right side, 8 different values downward (8 layers) for each different slab, so there will contains 111*8*456 =404928 values of data??
   
  and automatically read by MITgcm??
  
If you want to specify a "barotropic" open boundary in/outflow, then 
for each time slab you have to have a fields like this, eg. for a 
soutern or northern boundary:
   
  ==>"barotropic" open boundary in/outflow means constant value of T and S?? what the different with "baroclinic" open boundary in/outflow means dont held constant value of T and S?? this is what i want to ask too, about difference of baroclinic and barotopic treatment in MITgcm...(i sent in my previous message, subject : baroclinic, barotropic and bathyfile)
   
  for t=1:456
for z=1:nr
for x=1:nx
uob(x,z,t) = U(t)
end;end;end
if U(t) is your time series.
    ==>in what routine i wrote that code configuration???
  U(t) is just like my  U_AOK.IN?? means in every nx, in every nr has 1 value for each different slabs, so that file contains 1*1*456=456 value of data??is that what you mean about barotopic open boundary in/outflow??
  

  your File U_AOK.IN contains 1140 real*4 values with the following 
range/mean:
Min 4.2563e-31 Max 0.00017648 Mean 7.6306e-06 SD 3.1229e-05
  (At least that's what I read in with matlab:
> fid=fopen('U_AOK.IN','r','b');
> v=fread(fid,inf,'real*4');

  ==>uups sorry, i sent the wrong file...thats why the 
distribution looks strange....really sorry...i send it again for you...(U_A.OK), my U_A.OK only contains 456 values, min -4.1189, max 3.6017 , 
  in matlab :
  fid2  = fopen('U_A.OK','r','b');
W= fread(fid2,inf,'real*4');

) so that is 2.5 times the 456 number of times that you need (and the 
distribution looks strange). If you use this as U(t) then the model 
will only read the first 456 time slabs and disregard the rest, so no 
problem specifying it, but they will not affect your simulation. 
   
  ==>so there is no 2.5 times of numbers, it contains 456 time slabs for 1 point (tip point at west) for northern open boundary at the surface...
   
  The 
456 time slabs will be interpolate (linearly) in time between the 
hourly values to your 1.5sec time steps, but only specified at the 
open boundary. (not in the interior unless you use a sponge layer)
  ==>so to interpolate my file to my 1.5sec time steps just write in data file :
   
    # Time stepping parameters
  &PARM03
  niter0=0,
  nTimeSteps=1641600,
  deltaT=1.5,
  abEps=0.1,
  pChkptFreq=0.0,
  chkptFreq=0.0,
  dumpFreq=11160.,
  monitorFreq=2500.,
  # for time dependent open boundary conditions comment 
  # in the following three lines
  periodicExternalForcing=.TRUE.,
  externForcingPeriod=3600.,
  externForcingCycle=1641600.,
  &

   
  in data.obcs :
    # Open-boundaries
  &OBCS_PARM01
  OB_Jnorth=-1,
  OB_Jsouth=1,
  OB_Ieast=-1,
  OB_Iwest=1,
  # useOrlanskiEast=.TRUE.,
  # useOrlanskiWest=.TRUE.,
  # useOrlanskiNorth=.TRUE.,
  # useOrlanskiSouth=.TRUE.,
  # useOBCSsponge=.TRUE,
  useOBCSprescribe = .TRUE.,
  OBNuFile = U_A.OK',
  # OBSuFile = 'OBmeridU.bin',
  # OBWuFile = 'OBzonalU.bin',
  # OBEuFile = 'OBzonalU.bin',
  # OBWsFile = 'OBzonalS.bin',
  &
  
and then automatically will be interpolate lineraly by MITgcm??
  my U_A.OK in that configuration it doesnt contains (Nx,Nr,Nt) like you told me, just contains for 1 point for 456 time slabs,is that ok??will affect my simulation?? like i told you before in my previous message that i want to interpolate in spatial (inner of point A and point B for example) and in time (linear interpolation)...
   
   
  thats it for today martin, hope i dont disturb you with my questions...
  thank you so much...
  i'll wait for your next reply...
  best regards,
  rima
   

  
 

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