def mean_daily_air_temperature(t_min, t_max):
    """
    Calculation of the mean daily air temperature (Allen et al. 1998).

    NOTE: "For standardization, t_mean for 24-hour periods is defined as the
    mean of the daily maximum and minimum temperatures rather than as the
    average of hourly temperature measurements."

    Parameters
    ----------
    t_min : float
        Daily minimum air temperature (deg C).
    t_max : float
        Daily maximum air temperature (deg C).

    Returns
    -------
        Daily average air temperature (deg C).

    """
    return (t_max + t_min) / 2