The following is information on the different variables contained within the downloaded data file.

Inst: Serial number of instrument used to collect data

Site: 2 letter code indicating site of data collection

Level: Level of air sample. Level 1 is the higher level (> 100 m AGL) and level 2 is the lower level (30 m AGL).

YYYY: Year

DOY:  Day of Year

Hour: Hour of collection (UTC)

Time: Fractional day of year (UTC)

CO2(ppm): Hourly average CO2 mixing ratio.
	
QualityFlag:  (described in table below) 

Quality Flags
1: error estimated to be < 0.1 ppm
2: error estimated to be > 0.1 ppm but < 0.2 ppm
3: error estimated to be > 0.2 ppm but < 0.3 ppm
4: error estimated to be > 0.3 ppm but < 0.5 ppm
5: error estimated to be > 0.5 ppm (not recommended to be used; CO2 listed as -999)
0: missing data (CO2 listed as -999)

Please contact Natasha Miles (nmiles@psu.edu) if you have any questions regarding the data.