def reduce_wind_speed(wind_speed, wind_efficiency_curve_name='dena_mean'):
    r"""
    Reduces wind speed by a wind efficiency curve.

    The wind efficiency curves are provided in the windpowerlib and were
    calculated in the dena-Netzstudie II and in the work of Knorr
    (see [1]_ and [2]_).

    Parameters
    ----------
    wind_speed : pandas.Series or numpy.array
        Wind speed time series.
    wind_efficiency_curve_name : string
        Name of the wind efficiency curve. Use
        :py:func:`~.get_wind_efficiency_curve` to get all provided wind
        efficiency curves. Default: 'dena_mean'.

    Returns
    -------
    reduced_wind_speed : pd.Series or np.array
        `wind_speed` reduced by wind efficiency curve.

    References
    ----------
    .. [1] Kohler et.al.: "dena-Netzstudie II. Integration erneuerbarer
            Energien in die deutsche Stromversorgung im Zeitraum 2015 – 2020
            mit Ausblick 2025.", Deutsche Energie-Agentur GmbH (dena),
            Tech. rept., 2010, p. 101
    .. [2] Knorr, K.: "Modellierung von raum-zeitlichen Eigenschaften der
             Windenergieeinspeisung für wetterdatenbasierte
             Windleistungssimulationen". Universität Kassel, Diss., 2016,
             p. 124

    """
    # Get wind efficiency curve
    wind_efficiency_curve = get_wind_efficiency_curve(
        curve_name=wind_efficiency_curve_name)
    # Reduce wind speed by wind efficiency
    reduced_wind_speed = wind_speed * np.interp(
        wind_speed, wind_efficiency_curve['wind_speed'],
        wind_efficiency_curve['efficiency'])
    return reduced_wind_speed
r"""
    Reduces wind speed by a wind efficiency curve.

    The wind efficiency curves are provided in the windpowerlib and were
    calculated in the dena-Netzstudie II and in the work of Knorr
    (see [1]_ and [2]_).

    Parameters
    ----------
    wind_speed : pandas.Series or numpy.array
        Wind speed time series.
    wind_efficiency_curve_name : string
        Name of the wind efficiency curve. Use
        :py:func:`~.get_wind_efficiency_curve` to get all provided wind
        efficiency curves. Default: 'dena_mean'.

    Returns
    -------
    reduced_wind_speed : pd.Series or np.array
        `wind_speed` reduced by wind efficiency curve.

    References
    ----------
    .. [1] Kohler et.al.: "dena-Netzstudie II. Integration erneuerbarer
            Energien in die deutsche Stromversorgung im Zeitraum 2015 – 2020
            mit Ausblick 2025.", Deutsche Energie-Agentur GmbH (dena),
            Tech. rept., 2010, p. 101
    .. [2] Knorr, K.: "Modellierung von raum-zeitlichen Eigenschaften der
             Windenergieeinspeisung für wetterdatenbasierte
             Windleistungssimulationen". Universität Kassel, Diss., 2016,
             p. 124