kslice

KSLICE:  returns horizontal slice at particular layer.

 Works on either ECOM or SCRUM files.  For ECOM, the layer corresponds
 to sigma.  For SCRUM it corresponds to s_rho.  The function can also be
 used to read in 2D and 3D fields such as depth (h), or whatever.

 USAGE: [u,x,y]=kslice(cdf,var,[time],[layer])

 where 
   cdf:  file name for netCDf file (e.g. 'pom.cdf')
   var:  the variable to select (eg. 'salt' for salinity)
   time:   time step 
   layer:  sigma or s_rho layer (e.g 1 for top layer)

    
       Examples: 

          [s,x,y]=kslice('ecomsi.cdf','salt',2,3);
              returns the salinity field from the 3rd sigma level
              at the 2nd time step.

          [elev,x,y]=kslice('ecomsi.cdf','elev',4);
              returns the elevation field from the 4th time step

          [depth,x,y]=kslice('ecomsi.cdf','depth');
              returns the depth field

0001 function [u,x,y]=kslice(cdf,var,time,layer)
0002 %KSLICE:  returns horizontal slice at particular layer.
0003 %
0004 % Works on either ECOM or SCRUM files.  For ECOM, the layer corresponds
0005 % to sigma.  For SCRUM it corresponds to s_rho.  The function can also be
0006 % used to read in 2D and 3D fields such as depth (h), or whatever.
0007 %
0008 % USAGE: [u,x,y]=kslice(cdf,var,[time],[layer])
0009 %
0010 % where
0011 %   cdf:  file name for netCDf file (e.g. 'pom.cdf')
0012 %   var:  the variable to select (eg. 'salt' for salinity)
0013 %   time:   time step
0014 %   layer:  sigma or s_rho layer (e.g 1 for top layer)
0015 %
0016 %
0017 %       Examples:
0018 %
0019 %          [s,x,y]=kslice('ecomsi.cdf','salt',2,3);
0020 %              returns the salinity field from the 3rd sigma level
0021 %              at the 2nd time step.
0022 %
0023 %          [elev,x,y]=kslice('ecomsi.cdf','elev',4);
0024 %              returns the elevation field from the 4th time step
0025 %
0026 %          [depth,x,y]=kslice('ecomsi.cdf','depth');
0027 %              returns the depth field
0028 %
0029 
0030 
0031 if (nargin<2 | nargin>4),
0032   help kslice; return
0033 end
0034 
0035 % turn off warnings from NetCDf
0036 ncmex('setopts',0);
0037 
0038 ncid = ncmex('open', cdf, 'nowrite');
0039 if ( ncid == -1 )
0040     fprintf ( 'Could not open %s.\n', cdf );
0041     return;
0042 end
0043 
0044 %
0045 % Assume that a SCRUM file will always contain the 'xi_rho' dimension.
0046 % If we find it, assume that we've got a SCRUM file.
0047 [dimid, rcode] = ncmex('dimid', ncid, 'xi_rho');
0048 if ( dimid ~= -1 )
0049     ncmex ( 'close', ncid );
0050     switch ( nargin )
0051         case 2
0052             [u,x,y] = scrum_kslice ( cdf, var );
0053         case 3
0054             [u,x,y] = scrum_kslice ( cdf, var, time );
0055         case 4
0056             [u,x,y] = scrum_kslice ( cdf, var, time, layer );
0057     end
0058     return;
0059 end
0060 
0061 %
0062 % Assume that an ECOM file will always contain the 'xpos' dimensions.
0063 % If we find it, assume it is an ECOM file.
0064 [dimid, rcode] = ncmex('dimid', ncid, 'xpos');
0065 if ( dimid ~= -1 )
0066     ncmex ( 'close', ncid );
0067     switch ( nargin )
0068         case 2
0069             [u,x,y] = ecom_kslice ( cdf, var );
0070         case 3
0071             [u,x,y] = ecom_kslice ( cdf, var, time );
0072         case 4
0073             [u,x,y] = ecom_kslice ( cdf, var, time, layer );
0074     end
0075     return;
0076 end
0077 
0078 
0079 %
0080 % If we get this far, then neither file was recognizable.
0081 fprintf ( 'I can''t make sense out of %s???\n', cdf );
0082 help kslice;
0083 return;