data_file = StringIO(
    """ 1  253  2300   0    2.9  114.4  18.42  21.17
 1  253  2300  10   3.27  111.2  18.48  21.12
 1  253  2300  20   3.22  111.3  18.49  21.09
 1  253  2300  30   3.84  106.4  18.52     21
 1  253  2300  40   3.75  104.4  18.53  20.85
"""
    )
date_parser = lambda x: datetime.datetime.strptime('2001 ' + x, '%Y %j %H%M %S'
    )
columns = ['station', 'julian_day', 'hours', 'seconds', 'U', 'Ud', 'T', 'RH']
Convert date/time columns in Pandas dataframe