Compute background CO2 annual means for three flask sites from NOAA GML event data: QC flag positions, pair…

Compute background CO2 annual means for three flask sites from NOAA GML event data: QC flag positions, pair…: a task in pool-desk (Harbor dataset). I need background CO2 annual means for three of our flask sampling sites for 2021 to 2023, computed the way our group does it.