[ferret_users] Southern Hemisphere polar stereographic plot issue

[Geeta Persad <geeta.persad@xxxxxxxx>]

Hi All,

I am having a problem doing a polar stereographic plot for the Southern Hemisphere. Here is the code I am using:

SET MODE METADATA

user "all_vars.djf.nc"

GO mp_stereographic_south 180 50

GO mp_grid gz[d=1]

SET REGION/X=0:360/Y=90S:11S/Z=500/L=1

GO mp_aspect

let masked_gz1s = gz[d=1]*mp_mask

CONTOUR/NOAXES/NOLAB masked_gz1s, x_page, y_page

GO mp_land

GP mp_graticule 0 360 60 -11 -90 10 0.5

GO mp_label 180 6 0 0 0.2 "Southern Hem. DJF Geopotential Height at 500 mb" 

Where 'gz[d=1]' is the geopotential height variable in the 'all_vars.djf.nc' file.

This script throws the error

**ERROR: illegal limits: "(MP_Y[J=@MAX] + MP_..." does not exist at Y=-90:-11

                Axis extremes are Y=0.5:10000000

DEFINE VARIABLE/quiet mp_gtest = 50 - `(mp_y[j=@max] + mp_y[j=@min])/`

Command file, command group, or REPEAR execution aborted

I followed some earlier advice by Ansley from the archives indicating that putting the mp_grid statement before the set region and mp_aspect statement could solve this problem. However, the error is now being thrown following the call to mp_land. When I comment out mp_land, it is thrown after the call to mp_graticule. Ferret succeeds at running the contour command, though. I have also tried changing the standard parallel term in the call to mp_stereographic_south to '-50' instead of '50', but that doesn't seem to have an effect. 

Is there some other way in which mp_land and mp_graticule need to be called when using the Southern Hemisphere polar stereographic projection? Or is there some other visible error with my code? 

Thanks for your help!

~Geeta