[MITgcm-support] Definition of spatial boundary in EXF package

[Nicolas Bruneau]

Dear MITgcm support / users,

I just started to work with the MITgcm model using the EXF package and I 
would like to have some clarification about the boundary definitions. 
 From the documentation, I can read:
/field/_lon0 	$ xgOrigin+delX/2$ 	starting longitude of input
/field/_lon_inc 	$ delX$ 	increment in longitude of input
/field/_lat0 	$ ygOrigin+delY/2$ 	starting latitude of input
/field/_lat_inc 	$ delY$ 	increment in latitude of input
/field/_nlon 	$ Nx$ 	number of grid points in longitude of input
/field/_nlat 	$ Ny$ 	number of grid points in longitude of input


If my external forcing is, for example, a 1.5-degree resolution grid 
starting at 0 degree in longitude and -90 in latitude, do I need to 
define the spatial grid in data.exf as:
*atemp_lon0    = .75  (i.e. 0 + dX / 2)*
  atemp_lon_inc = 1.5
*atemp_lat0    = -89.25*
  atemp_lat_inc = 120*1.5
  atemp_nlon    = 240
  atemp_nlat    = 121

or do I define it as:
*atemp_lon0    = 0*
  atemp_lon_inc = 1.5
*atemp_lat0    = -90*
  atemp_lat_inc = 120*1.5
  atemp_nlon    = 240
  atemp_nlat    = 121

When I'm looking the subroutine exf_interp.F, it looks that the "x_in" 
variable represents the coordinates of the input and in such a case, I 
would think the second definition (atemp_lon0 = 0) is the good one but 
following the documentation, it looks that the first one is the good 
one. So I imagine, I didn't get something.

I would be really grateful for some help. Looking forward to hearing 
from you.

-- 
BAS <http://www.antarctica.ac.uk/> 	*Dr Nicolas Bruneau*
British Antarctic Survey
High Cross, Madingley Road, Cambridge, CB3 0ET, UK
Email: nicbru at bas.ac.uk <mailto:nicbru at bas.ac.uk>
Phone: +44 (0) 1223 22 13 27


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