! inspired by Andrew T. Wittenberg: Visualizing the GFDL OM3 tripolar grid with Ferret
! http://www.gfdl.noaa.gov/~atw/ferret/tripolar
! 
use ocean_static.nc
sh d
let checker_t = missing(0*ht,2) + mod(i+j,2)
def grid/x=ht/y=ht g_t
let x_t=geolon_t
let y_t=geolat_t
let xv_t=geolon_c
let yv_t=geolat_c
palette land_sea
can region; set region/k=1/l=1/y=60.01n:89.99n
go mp_stereographic_north 350
let mp_lambda = xv_t * deg2rad
let mp_phi = yv_t * deg2rad
set grid g_t
go mp_aspect
shade/noax/nokey checker_t, x_page, y_page
ppl color 6 100 100 100
go mp_graticule 0 360 20 60 80 10 6