the cdo sinfo time of ERA5 is strange

[xu_ru]

Hi, everyone,

I download ERA5 data using the below code, i download for August,2022,

i submite the job for 3 times, 1 for 0801-0810, 2 for 0811-0820, 3 for 0821-0831,

START_DATE 20220817
END_DATE 20220825
DTIME 3
TYPE AN AN AN AN AN AN AN AN
TIME 00 03 06 09 12 15 18 21
STEP 00 00 00 00 00 00 00 00
ACCTYPE FC
ACCTIME 06/18
ACCMAXSTEP 12
CLASS EA
STREAM OPER
GRID 0.5
LEFT -179.
LOWER -90.
UPPER 90.
RIGHT 180.
LEVELIST 1/to/137
RESOL 159
ETA 1
CWC 1
PREFIX EA
ECTRANS 1
FORMAT GRIB2

when i checked the output using cdo sinfo, the result of EA22082218
is:

Time coordinate :
                             time : unlimited steps
 RefTime =  2022-08-22 18:00:00  Units = hours  Calendar = proleptic_gregorian
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss
  2022-08-22 18:00:00  2022-08-20 03:00:00  2022-08-20 06:00:00  2022-08-20 09:00:00
  2022-08-20 12:00:00  2022-08-20 15:00:00  2022-08-20 18:00:00  2022-08-20 21:00:00

the time stamp with 2022-08-22 18:00:00 is acceptable, but other time stamp is strange. Why there exist the 2022-08-20 time stamp.