SGP/PGS/C1 - Reprocessing User Notes

Time Variables - to make the PGS system more consistent with LBNL's other data streams, 
the variable 'yyyymmddhhmmss' was renamed 'yyyydddhhmmss'. Also, at the bottom of each 
file, variables 'yyyy','mon','hour','min' were added for those users who prefer to use these 
variables instead. The new 'time' variable (seconds since midnight of the start of file) 
was added to make files compatible with the new recommendations.

Quality Control Flags - to prevent confusion, the quality control flags 'qc_co2ppm' and 
'qc_sum_co2' were combined. The flag 'qc_sum_co2' was elliminated and 'qc_co2ppm' now 
performs range checking on 'co2ppm' variable as well as checking values of all dependencies' 
qc flags.

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• longitude of instument location(site_longitude)
• calibration coefficient 3 (quadratic fit) 90% confidence limit(coeff3_se)
• calibration coefficient 1 (quadratic fit) 90% confidence limit(coeff1_se)
• Temperature in refigerator(t_refrig)
• MFRSR channels(channel)
• Pressure of channel 2(pres2)
• surface pressure(pres1)
• Pressure of channel 4(pres4)
• Slope of CO2 readings during last 30sec of 3min period of raw data(co2mv_slope)
• r-squared of quadratic fit(r2)
• Pressure of channel 3(pres3)
• calibration coefficient 3 (quadratic fit)(coeff3)
• calibration coefficient 2 (quadratic fit)(coeff2)
• calibration coefficient 1 (quadratic fit)(coeff1)
• pressure inside the IRGA box measured by the pressure controller(pres_ctrlr)
• p-value of co2 readings during the last 30sec of 3min period of raw data(co2mv_slope_pval)
• flag indicating which channel isotope sample was taken from(iso)
• latitude of instument location(site_latitude)
• calculated concentration of CO2(co2ppm)
• reading of CO2 in mV(co2mv)
• Second level of QC, see reject_flag_explanation global attribute(reject_flag)
• calibration coefficient 2 (quadratic fit) 90% confidence limit(coeff2_se)
• reference CO2 reading in mV(ref)
• First level of QC, see warn_flag_explanation global attribute(warn_flag)
• height of base of instrument tower(site_elevation)
• flow rate measured by the mass flow controller(flow_rate)
• standard deviation of co2mv(co2mv_se)
• Date and time in alternate form(yyyymmddhhmmss)
• 90% confidence limint of co2mv_slope(co2mv_slope_se)
• temperature of the IRGA(t_irga)
• Number of measurements for indicated channel(nmeas)
• adjusted CO2(adj)
• 90% confidence limit of co2ppm(co2ppm_se)
• base time in epoch(base_time)