I am trying to understand “AVG_FILE_ENDTIME” option further. I see the default value is N. I have tried it and it seems it pushes the ACONC hours, 1 hour forward. I was wondering how this option could be useful? Some collaborators of ours actually put this option to Y and use it, so I am trying to make sense of it.
I would appreciate if you could guide me further.
Yes, setting this variable to Y will cause the time stamps in the ACONC file to be the end of the hour over which the averaging occurs rather than the default behavior of using the beginning of the hour. This is documented in Appendix A of the User Guide.
Earlier version of CMAQ (maybe up to CMAQv5.1, but I don’t recall) had a different default behavior, so conceivably modifying the setting of this option in the current version of CMAQ could be useful if one wanted to directly compare ACONC files generated by the newer version against existing ACONC files created by an earlier version. For comparison of model output to measured hourly average concentrations collected at typical monitoring networks in the U.S. (e.g. AQS), the current default behavior of using the time stamp at the beginning of the hour is most appropriate - see this note.