@marqh You could slightly refactor this to be ...
```
    projections = dict(Mollweide=ccrs.Mollweide(),
                       PlateCarree=ccrs.PlateCarree(),
                       NorthPolarStereo=ccrs.NorthPolarStereo(),
                       Orthographic=ccrs.Orthographic(central_longitude=-90,
                                                      central_latitude=45))
```