grdfilter - Filter a . grd file in the Time domain grdfilter input _ file . grd -D flag -F < type >< width > -G output _ file . ... The output . ... grd The file of points to be filtered. D Distance flag tells how grid (x,y) relates to filter width as follows: flag = 0: grid (x,y) same units as width , Cartesian distances. flag = 1: grid (x,y) in degrees, width in kilometers, Cartesian distances. flag = 2: grid (x,y) in degrees, width in km, dx scaled by cos(middle y), Cartesian distances. ...