def lonlat2xyz(lons, lats):
    """Convert lons and lats to cartesian coordinates."""
    R = 6370997.0
    x_coords = R * da.cos(da.deg2rad(lats)) * da.cos(da.deg2rad(lons))
    y_coords = R * da.cos(da.deg2rad(lats)) * da.sin(da.deg2rad(lons))
    z_coords = R * da.sin(da.deg2rad(lats))
    return x_coords, y_coords, z_coords
Convert lons and lats to cartesian coordinates.