FAIR USE POLICY:

If the data are obtained for 
potential use in a publication or presentation, kindly inform Penn State 
personnel (co2data@meteo.psu.edu) of the nature of this work.  We reserve 
the right to make corrections to the data based on scientific grounds, 
e.g., recalibration of standard gases or discovery of operational issues 
not known at the time of the release.  

Thanks!
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The files in this directory are calibrated CO2 dry mole fraction hourly files 
for the three sites. CH4 in sce02-walker-bldg is dry mole fraction and 
calibrated. CH4 in sce01-rock-springs and sce03-houserville is dry mole 
fraction but not calibrated. DOY (fractional day of year) is in GMT for all 
files.

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CALIBRATION UPDATE (03/24/2021): The measured mole fraction was converted from traceable to the WMO X2007 scale (CO2) to WMO X2019 scale (CO2), following Hall et al. (2020) using the linear function: X2019=1.00079 * X2007 - 0.142 (ppm)

CITATION:
Hall, B. D., Crotwell, A. M., Kitzis, D. R., Mefford, T., Miller, B. R., Schibig, M. F., & Tans, P. P. (2020). Revision of the WMO/GAW CO 2 calibration scale. Atmospheric Measurement Techniques Discussions, 1-33. DOI: https://doi.org/10.5194/amt-2020-408

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In the directory "raw", we archive the raw data. To go from the raw files to 
the calibrated files (as above), the following information is needed:


For instruments FCDS2048 and FCDS2049, use JULIAN_DAYS (which is in GMT).
The values reported in the files are CO2_dry and CH4_dry. 
CO2_DRY was calculated using CO2 (ppm) and H2O (%), following Miles et al., Atmos. 
Meas. Tech., 2018.  For these instruments, 12CH4 is reported.  Use the 
istopic ratio to get total CH4.    

For instrument CFADS2155, use FRAC_DAYS_SINCE_JAN1 (in GMT, but add 1 day to 
get to JULIAN_DAYS).  Use CO2_dry, which already has the water correction 
applied.

Calibrations:
Add 0.1 ppm to FCDS2048 (Rock Springs)
Add 2.3 ppm to FCDS2049 (Houserville)
Calibration already applied to CFADS2155 (Walker Building)