@classmethod
def request_data(cls, time, site_id, **kwargs):
    """Retrieve upper air observations from Iowa State's archive for a single station.

        Parameters
        ----------
        time : datetime
            The date and time of the desired observation.

        site_id : str
            The three letter ICAO identifier of the station for which data should be
            downloaded.

        kwargs
            Arbitrary keyword arguments to use to initialize source

        Returns
        -------
            :class:`pandas.DataFrame` containing the data

        """
    endpoint = cls()
    df = endpoint._get_data(time, site_id, None, **kwargs)
    return df
