id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
638	IMPORTANT: Changed the default values in contact.m	arango	arango	" * Changed the default input argument values in the Matlab script '''contact.m'''. This script is used to compute contact points data  needed in nesting applications. It also generates the Nesting Grids Connectivity NetCDF file  '''NGCNAME''' for ROMS.

 The script '''contact.m''' has several input arguments:
{{{
[S, G] = contact  (Gnames, Cname, Lmask, MaskInterp, Lplot)
}}}
 see [https://www.myroms.org/wiki/index.php/Grid_Processing_Scripts WikiROMS] for more information.

 The '''!MaskInterp''' switch is now changed to '''false''' by default.  It is used in refinement applications to compute the land/sea masks at '''U'''- and '''V'''-points.  If '''false''', the '''U'''- and '''V'''-mask are computed from the interpolated '''RHO'''-mask using script '''uvp_masks'''. Otherwise if true, it is interpolated from the coarser grid.  This is done in internal function '''refine_coordinates''' (around line 813 in '''contact.m'''):
{{{
R.mask_rho = interp2(XrC', YrC', G(dg).mask_rho', XrF, YrF, 'nearest'); 
 
if (MaskInterp), 
  R.mask_psi = interp2(XpC', YpC', G(dg).mask_psi', XpF, YpF, 'nearest'); 
  R.mask_u   = interp2(XuC', YuC', G(dg).mask_u'  , XuF, YuF, 'nearest'); 
  R.mask_v   = interp2(XvC', YvC', G(dg).mask_v'  , XvF, YvF, 'nearest'); 
else 
  [umask, vmask, pmask] = uvp_masks(R.mask_rho); 
  R.mask_psi = pmask; 
  R.mask_u   = umask; 
  R.mask_v   = vmask; 
end
}}}
 Notice that only the finer grid mask at '''RHO'''-points is interpolated from the coarse grid.  The other masks are computed using '''uvp_masks''' for consistency. Of coarse, this is only relevant when there are land/sea mask features in any of the refinement grid physical boundaries and/or contact regions.

 '''This is very important, and the users need to check the masks in the nesting contact regions'''... See new script '''check_nest_mask.m''' described below.

 In addition, the input argument for the '''Lplot''' switch is turned off ('''false''') by default.  There are a lot of plots that slow down the computations and are very tricky to check.  It require expertise in ROMS nesting strategies to check for correctness.  There are still few simpler plots that are still processed.  The user does not have control on them.

 * '''grid/check_nest_masks.m''': Checks land/sea masks in nesting contact regions. In particular, it can be used to examine the nesting grids connectivity when there are land/sea mask features in the contact regions. A plotting section is provided as a guideline.  Users may need to adapt it for their particular application.

----

'''WARNING''': if you computed the contact points NetCDF file with '''!MaskInterp=true''' (default behavior in previous versions of '''contact.m'''), you need to recompute the contact points NetCDF file if your application have land/sea mask points in the contact region."	upgrade	closed	major	Matlab Processing Scripts	Matlab	3.7	Done