Interpolate using cubic spline approximation
        Returns the same as interpolate(lons,lats,data,order=3)

def interpolate_cubic(self, lons, lats, data):
        """
        Interpolate using cubic spline approximation
        Returns the same as interpolate(lons,lats,data,order=3)
        """
        return self.interpolate(lons, lats, data, order=3)