II. Data set  fhc00.v1:

This data set contains fluxes of biogenic volatile organic compounds measured between 
April 21 and November 1, 2000. All values are reported in mg carbon per square meter and 
hour under standard conditions (0 deg C and 1013 mbar). 
All compounds have been identified by retention time compared to addition of standards to 
real air samples. It is still possible that co-elutions of other unidentified compounds 
could affect the reported mixing ratios or fluxes (see MACR documentation). Calibration 
was carried out as described in the file readme_hc00v1.txt. 

All samples that contain standard additions have been set "NA".

Relaxed Eddy Accumulation (REA) Fluxes were calculated as the difference between updraft 
and downdraft mixing ratios times the standard deviation of the vertical wind speed during
each half-hour measurement times the b-factor, calculated from simultaneous heat flux
measurements. Differences between the chromatographic channels were adjusted for by a
multi-step procedure as follows:
1. Mixing ratios of Methacrolein (MACR), a compound whose flux was assumed to be negligible,
  in up- and downdrafts were used to create a correction vector, the ratio between the down- 
  and up-channel, similar to 1999. The vector was subsequently smoothed to account for 
  MACRs own random variability.
2. The correction factor was adjusted during individual periods by linearly comparing it 
  to the specific compounds own individual channel ratio as measured out of the deadband 
  during calibration runs that did not contain that specific compound.
3. Downchannel data was multiplied by the correction vector before substracting it from 
  the up-channel.
4. An extra column was attached to each flux vector. It contains a flag, which is "1" for 
  flux data acquired during times when the interchannel ratio, after correction, was still
  outside statistical limits, generally designating an outlier (often >90 and <10% quantiles).
5. The monoterpenes alpha- and beta-pinene contain two flags each, whereby flag2 comprises
  ALL data that is potentially questionable.

Compound description (numbering refers to column number):
 (precision is dominantly based on the precision of each mixing ratio measurement, while
 the minimum detectable flux - at the 90% level - is based on the compound's inter-channel 
 ratio, i.e. the minimum detectable mixing ratio DIFFERENCE between the channels, not 
 including outliers in the analysis)
1. "time": Day of year + decimal day fraction. Note that the time line is NOT based on 
	local summer time (PDT), but on local standard time (Pacific Standard Time = PST); 
	value is centered on the full hour.

2. "hour": Hour of measurement during that day in decimals; value is centered at 15 min 
	after the full hour, the middle of the actual sampling interval.

3. "methanol": CH3OH, fluxes are calculated from the corrected methanol mixing ratios, and may
	therefore be underestimated as the correction is based on the acetone data of the
	same channel, and acetone does show a flux as well;
	minimum detectable flux: 0.04 mg C m-2 h-1

4. "flag_methanol": Flag for Menthanol, see point 4 under REA above.

5. "ethanol": C2H5OH, partially coeluting with benzene;
	minimum detctable flux: 0.03 mg C m-2 h-1

6. "flag_ethanol": Flag for ethanol, see point 4 under REA above.

7. "acetone": (CH3)2CO, most abundant ketone measured; 
	minimum detectable flux: 0.03 mg C m-2 h-1

8. "flag_acetone": Flag for acetone, see point 4 under REA above.

9. "acetaldehyde": CH3CHO, most abundant alkanal measured; 
	minimum detectable flux: 0.025 mg C m-2 h-1

10. "flag_acetaldehyde": Flag for acetaldehyde, see point 4 under REA above.

11. "Methylbutenol": MBO, C5H9OH, dominant local emission compound from 
	ponderosa pine; minimum detectable flux: 0.01 mg C m-2 h-1

12. "flag_Methylbutenol": Flag for Methylbutenol, see point 4 under REA above.

13. "a-pinene": alpha-pinene, C10H16, monoterpene; emitted from ponderosa pine and 
	other trees in the area; minimum detectable flux: <0.01 mg C m-2 h-1

14. "flag1_a-pinene": Flag1 for a-pinene, see point 4 under REA above.

15. "flag2_a-pinene": Flag2 for a-pinene, see point 5 under REA above.

16. "b-pinene": beta-pinene, C10H16, monoterpene; emitted mostly from ponderosa 
	pine in the area; minimum detectable flux: <0.015 mg C m-2 h-1

17. "flag1_b-pinene": Flag1 for b-pinene, see point 4 under REA above.

18. "flag2_b-pinene": Flag2 for b-pinene, see point 5 under REA above.

19. "3-carene": Delta-3-carene, C10H16, monoterpene; emitted mostly from ponderosa 
	pine in the area; Note that there was a systematic channel difference
	that rendered much of this data not useful; the remaining data still showed a
	rather poor inter-channel comparison; the minimum detectable flux
	was estimated to ~0.01 mg C m-2 h-1

20. "flag_3-carene": Flag for 3-carene, see point 4 under REA above.