data = (
    '\nABCD 15:010:00000 2564.6   4.0  -0.380  0.417  -1.313  0.520\nABCD 15:010:00300 2564.3   3.7  -0.389  0.396  -1.318  0.503\nABCD 15:010:00600 2563.9   3.5  -0.397  0.389  -1.324  0.496\nABCD 15:010:00900 2563.9   3.3  -0.411  0.368  -1.322  0.476\nABCD 15:010:01200 2563.8   3.0  -0.425  0.361  -1.320  0.466\nABCD 15:010:01500 2563.9   2.8  -0.432  0.340  -1.312  0.447\nABCD 15:010:01800 2564.3   2.6  -0.439  0.334  -1.304  0.439\n'
    )
names = ['Site', 'Epoch', 'TroTot', 'Stdev', 'TgnTot', 'TgnStd', 'TgeTot',
    'TgeStd']
df = pd.read_csv(StringIO(data), header=None, names=names, delim_whitespace
    =True, parse_dates=['Epoch'], date_parser=date_parser)
print(df)
Pandas date_parser function for year:doy:sod format