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PRELIMINARY DATA:  DO NOT DISTRIBUTE
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National Oceanic and Atmospheric Administration (NOAA)
Climate Monitoring and Diagnostics Laboratory (CMDL)
Carbon Cycle Greenhouse Gases (CCGG)

Correspondence concerning these data should be directed to:

Dr. Arlyn E. Andrews 
NOAA Climate Monitoring and Diagnostics Laboratory
325 Broadway, R/CMDL1
Boulder, CO  80305
U.S.A.

email: Arlyn.Andrews@noaa.gov


********************* USE OF ESRL/GMD CCGG DATA *********************
 
These data are made freely available to the public and the
scientific community in the belief that their wide dissemination
will lead to greater understanding and new scientific insights.
The availability of these data does not constitute publication
of the data.  We rely on the ethics and integrity of the user to
assure that ESRL/GMD receives fair credit for our work.  If the data
are obtained for potential use in a publication or presentation,
ESRL/GMD should be informed at the outset of the nature of this work.
If the ESRL/GMD data are essential to the work, or if an important
result or conclusion depends on the ESRL/GMD data, co-authorship may
be appropriate.  This should be discussed at an early stage in
the work.  Manuscripts using the ESRL/GMD data should be sent to ESRL/GMD 
for review before they are submitted for publication so we can
insure that the quality and limitations of the data are accurately
represented. 

*********************** RECIPROCITY AGREEMENT *********************
 
Use of these data implies an agreement to reciprocate.
Laboratories making similar measurements agree to make their
own data available to the general public and to the scientific
community in an equally complete and easily accessible form.
Modelers are encouraged to make available to the community,
upon request, their own tools used in the interpretation
of the ESRL/GMD data, namely well documented model code, transport
fields, and additional information necessary for other
scientists to repeat the work and to run modified versions.
Model availability includes collaborative support for new
users of the models.
 
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Description of Tower CO2 data file format
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Column 1:      Year
Column 2:      Month
Column 3:      Day
Column 4:      Hour
Column 5:      Minute
Column 6:      Second
Column 7:      Sampling Level
Column 8:      CO2 dry air mole fraction (ppm)
Column 9:      Total Uncertainty estimate (ppm)
Column 10:     Analytical Uncertainty estimate (ppm)
Column 11:     Quality Flag

Sampling Level:  Air is sampled from 6 heights along the WLEF-TV 
                 broadcasting tower.  Height above ground level is 
   		 given below.
		 	 1=11m
			 2=30m
			 3=76m
			 4=122m
			 5=244m
			 6=396m
		 
CO2 Dry Air Mole Fraction:  The CO2 abundance is given as a mole fraction 
with units of parts per million (ppm).  This value corresponds to the number 
of CO2 molecules per 1 million molecules of dry air.  Each data point 
represents a 30 sec average of data collected at 5 Hz.
		 
Uncertainty Estimates:  The uncertainty estimate attempts to account for 
known quantifiable errors in the CO2 measurements. Uncertainty contributions 
include uncertainty in the calibration scale, drift in the CO2 analyzer 
baseline and gain between calibrations, lack of equilibration of air samples 
or standards, curve fitting errors, extrapolation error for samples that are 
outside of the calibrated range, differences in H2O content of samples and 
standards, and real natural variability of the CO2 abundance during the 
measurement period (30 sec). Calibration scale uncertainty is 0.07 ppm; 
analyzer drift uncertainty is typically less than 0.1 ppm; standard 
equilibration uncertainty, curve fitting errors, and differences in water 
content between samples and standards are typically each < 0.05 ppm.  Sample 
equilibration error/atmospheric variability is the largest contribution to 
the total uncertainty.  These terms cannot be reliably separated.  Column 9 
contains the Total Uncertainty estimate and this is the value that should be 
used in scientific analysis.  Column 10 is the "analytical uncertainty 
estimate" and does not include sample equilibration error or atmospheric 
variability.  Column 10 is intended for ESRL/GMD diagnostic purposes only.

Quality Flag:  111= flow through licor < 50 sccm (normal flow=100sccm)
               222= temporal gap in calibrations precludes reliable calculation
               333= calculated CO2 mole fraction outside range of standards
               900= normal operation
               901= flow through licor 50-95 sccm (normal flow=100 sccm)
	       903= data outside of calibrated range
               904= leak suspected
               905= other known problem with analyzed values