OBSGRID run errors

[Henry Chen]

Hi, I was running OBSGRID for a period of 1 year. The time interval is 6 hours, and i encountered error as follows:

Time period #00998 is for date 2018-08-31_18:00:00
Time period #00999 is for date 2018-09-01_00:00:00
Time period #01000 is for date 2018-09-01_06:00:00
Time period #01001 is for date 2018-09-01_12:00:00
STOP ERROR_EXIT in error_handler

------------------------------------------------------------
ERROR EXIT
Too many time periods for processing have been specified.

It seems that the program allows only 1000 time periods. Is there any option to change this restriction or I have to run obsgrid with intervals?
If so, could wrfsdda files be merged or I need to run WRF with same intervals as well?
Thank you!