def lookup_projection(projection_code):
    """Get a Cartopy projection based on a short abbreviation."""
    import cartopy.crs as ccrs
    projections = {'lcc': ccrs.LambertConformal(central_latitude=40,
        central_longitude=-100, standard_parallels=[30, 60]), 'ps': ccrs.
        NorthPolarStereo(central_longitude=-100), 'mer': ccrs.Mercator()}
    return projections[projection_code]
