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Changeset 5117 – NEMO

Changeset 5117

2015-03-03T13:31:02+01:00 (9 years ago)

#1472. Branch dev_r5087_NOC2_JATTR. Submit documentation prior to final testing and merge back to the trunk

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1 edited


  • branches/2015/dev_r5087_NOC2_JATTR/DOC/TexFiles/Chapters/Chap_MISC.tex

    r4147 r5117  
    141141computational domain is laid out on local processor memories following a 2D  
    142142horizontal splitting. % (see {\S}IV.2-c) ref to the section to be updated 
     144\subsection{Simple subsetting of input files via netCDF attributes} 
     146The extended grids for use with the under-shelf ice cavities will result in redundant rows 
     147around Antarctica if the ice cavities are not active. A simple mechanism for subsetting 
     148input files associated with the extended domains has been implemented to avoid the need to 
     149maintain different sets of input fields for use with or without active ice cavities. The 
     150existing 'zoom' options are overly complex for this task and marked for deletion anyway. 
     151This alternative subsetting operates for the j-direction only and works by optionally 
     152looking for and using a global file attribute (named: \np{open\_ocean\_jstart}) to 
     153determine the starting j-row for input. The use of this option is best explained with an 
     154example: Consider an ORCA1 configuration using the extended grid bathymetry and coordinate 
     164\noindent These files define a horizontal domain of 362x332. Assuming the first row with 
     165open ocean wet points in the non-isf bathymetry for this set is row 42 (Fortran indexing) 
     166then the formally correct setting for \np{open\_ocean\_jstart} is 41. Using this value as the 
     167first row to be read will result in a 362x292 domain which is the same size as the original 
     168ORCA1 domain. Thus the extended coordinates and bathymetry files can be used with all the 
     169original input files for ORCA1 if the ice cavities are not active (\np{ln\_isfcav = 
     170.false.}). Full instructions for achieving this are: 
     172\noindent Add the new attribute to any input files requiring a j-row offset, i.e: 
     177ncatted  -a open_ocean_jstart,global,a,d,41  
     178ncatted  -a open_ocean_jstart,global,a,d,41 
     182\noindent Add the logical switch to \ngn{namcfg} in the configuration namelist and set true: 
     187\noindent Note the j-size of the global domain is the (extended j-size minus 
     188\np{open\_ocean\_jstart} + 1 ) and this must match the size of all datasets other than 
     189bathymetry and coordinates currently. However the option can be extended to any global, 2D 
     190and 3D, netcdf, input field by adding the: 
     198optional argument to the appropriate \np{iom\_get} call and the \np{open\_ocean\_jstart} attribute to the corresponding input files. It remains the users responsibility to set \np{jpjdta} and \np{jpjglo} values in the \np{namelist\_cfg} file according to their needs. 
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