Plotting Sandwell/Smith Mercator img grids

	# Gravity in tasman_grav.nc is in 0.1 mGal increments and the grid
	# is already in projected Mercator x/y units.

	# Make a suitable cpt file for mGal
	grav_cpt = makecpt(range=(-120,120), cmap=:rainbow)

	# Since this is a Mercator grid we use a linear projection
	grdimage("@tasman_grav.nc=ns+s0.1", frame=:none, shade=:default,
             proj=:linear, figscale=0.635)

	# Then use gmt pscoast to plot land; get original -R from grid remark
	# and use Mercator gmt projection with same scale as above on a spherical Earth
	R = grdinfo("@tasman_grav.nc", nearest=:i)
	R = R[1].text[1][3:end]
	coast!(region=R, proj=:merc, figscale=0.635, land=:black, river_fill=:white,
           frame=(axes=:WSne, annot=10, ticks=5), res=:high,
           par=(FORMAT_GEO_MAP="dddF", PROJ_ELLIPSOID=:Sphere))

	# Put a color legend in top-left corner of the land mask
    colorbar!(region=R, pos=(inside=true, anchor=:TL, offset=1, length=(5, 0.4)),
              xaxis=(annot=50, ticks=10), ylabel="mGal", shade=true,
              box=(pen=1, fill=:white), show=true)