Fix contours on global data plot

[brian-rose]

Closes #652

When creating a mesh of data on a lat-lon grid at the end of the Cartopy notebook, just avoid having data exactly at the poles to work around a Mollweide projection limitation.

Or, maybe better alternative, don't use Mollweide for this example!

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[r-ford]

Thanks for figuring this out @brian-rose! I feel like this has the potential to confuse someone new to Cartopy, since this is a bug for a specific projection that might get fixed one day and not a general rule about avoiding data at the poles in plots. I think the simplest fix would be to change the projection to one that works and still distorts the contours a bit.

[brian-rose]

Thanks for figuring this out @brian-rose! I feel like this has the potential to confuse someone new to Cartopy, since this is a bug for a specific projection that might get fixed one day and not a general rule about avoiding data at the poles in plots. I think the simplest fix would be to change the projection to one that works and still distorts the contours a bit.

Fair point! I'll push an update that switches to a different projection.

[brian-rose]

The latest commit here switches over to the Equal Earth projection, with a scholarly reference to boot!

[kafitzgerald]

Looks great!