grdlandmask - Create "wet-dry" mask grdfile from shoreline data base. grdlandmask -G mask _ grd _ file ] -I xinc [ m|c ][/ yinc [ m|c ]] -R west / east / south / north [ r ] [ -A min _ area [/ min _ level / max _ level ] ] [ -D resolution ] [ -F ] [ -N maskvalues [ o ] ] [ -V ] grdlandmask reads the selected shoreline database and uses that information to decide which nodes in the specified grid are over land or over water. ... The resolution drops off by ~80% between data sets. Default is l ]. ...