def format_index(data):
year = data.year.apply(str)<EOL>jday = data.jday.apply(lambda x: '<STR_LIT>'.format(x))<EOL>hours = data.hour.apply(lambda x: '<STR_LIT>'.format(x))<EOL>minutes = data.minute.apply(lambda x: '<STR_LIT>'.format(x))<EOL>index = pd.to_datetime(year + jday + hours + minutes, format="<STR_LIT>")<EOL>data.index = index<EOL>data = data.tz_localize('<STR_LIT>')<EOL>return data<EOL>
Create UTC localized DatetimeIndex for the dataframe.

    Parameters
    ----------
    data: Dataframe
        Must contain columns 'year', 'jday', 'hour' and
        'minute'.

    Return
    ------
    data: Dataframe
        Dataframe with a DatetimeIndex localized to UTC.