I. Data set  hc00.v1:
General:
This data set contains mixing ratios of biogenic and anthropogenic volatile organic 
compounds measured between April 21 and November 1, 2000. All values are reported in ppb. 
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 against one or more diluted ppm-Standards as described below. All mixing 
ratio data are from "up-drafts" (see previous publications) as that was generally the
cleaner chromatographic channel. Some very high and very low mixing ratios that were 
identified as outliers have been set "NA". All samples that contain standard additions 
have been set "NA".
The microtraps were changed several times during the measurement period. Chromatographic 
columns (Rtx-Wax columns, 60 m, wide-bore: 0.53 mm ID) were cut when necessary to remove 
degraded parts. 

Note: All chromatograms have been integrated manually for proper identification and 
quantification. A small amount of human error, however, is statistically unavoidable. 
Zero mixing ratios were not set "NA" unless obviously in error.

Compound description (numbering refers to column number):
(Calibration Standard(s) used for identification and quantification is(are) given in 
parentheses behind compound name; precision is given as approximate 95% confidence interval)
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.

Isoprene and its oxidation products:
3. "isoprene" (S1, OVOC): C5H8, biogenic VOC; among the most precisely measured compounds; 
	stable response throughout the whole data set; long-term precision: 5-10%.

4. "MVK": Methyl-vinyl-ketone, C4H6O, major isoprene oxidation product; the compound is 
	not calibrated with an external standard, but its FID-response is assumed to 
	equal that of MACR (see next).

5. "MACR" (S1, OVOC, BPIN): Methacrolein, C4H6O, major isoprene oxidation product; 
	Note: The theoretical response factor based on the relative FID response of MACR 
	versus isoprene was used for calibration rather than the actually measured 
	response factors according to our standard (would have been ~20% higher). ; long-term precision: 5-10%


Oxygenated VOCs:
6. "methanol" (OVOC): CH3OH, most abundant VOC; has both biogenic and anthropogenic 
	sources and long atmospheric lifetime; mixing ratios should be viewed with some 
	caution, as they are empirically corrected for the coeluting compounds 
	methyl-ethyl-ketone, and 3-methyl-furan; varying occurrence in blank samples;
	long-term precision: ~5% (mostly due to MEK in the same standard).

7. "ethanol" (OVOC): C2H5OH, partially coeluting with benzene; mixing ratios may 
	slightly overestimate actual abundance; sources are dominantly biogenic; 
	small and varying occurrence in blank samples. No consistent calibration.

8. "acetone" (S1, OVOC): (CH3)2CO, most abundant ketone measured; among the most 
	precisely measured compounds; very long atmospheric lifetime; major MBO 
	oxidation product; no known chromatographic interferences; long-term precision: 5-10% 

9. "acetaldehyde" (OVOC): CH3CHO, most abundant alkanal measured; has anthropogenic 
	and biogenic sources; mixing ratios might be overestimating actual abundance 
	due to a minor coelution with an unknown compound; small and varying occurrence 
	in blank samples; long-term precision: ~10%. 

10. "MBO" (MBO, BPIN): Methylbutenol, C5H9OH, dominant local emission compound from 
	ponderosa pine; most abundant reactive hydrocarbon; long-term precision: 10-15%.


Monoterpenes (Note: all monoterpenes, but in particular 3-carene and limonene, show 
breakthrough characteristics at higher (>2-3 ppb) mixing ratios):
11. "a-pinene" (S1, S2): a-pinene, C10H16, monoterpene; emitted from ponderosa pine and 
	other trees in the area; no known chromatographic interferences; highest 
	reliability among the monoterpenes measured; long-term precision: ~5%.

12. "b-pinene" (BPIN): b-pinene, C10H16, monoterpene; emitted mostly from ponderosa 
	pine in the area; no known chromatographic interferences; b-pinene shows issues 
	of instability and conversion (often into another monoterpene) presumably 
	during desorption from the microtraps, wherefore the given mixing ratios may 
	partially be underestimates; long-term precision: 20-25%.

13. "3-carene" (S2): D-3-carene, C10H16, monoterpene; emitted mostly from ponderosa 
	pine in the area; known chromatographic interference from m-xylene; D-3-carene 
	shows issues of breakthrough at higher mixing ratios, wherefore the given 
	mixing ratios may partially be underestimates, and obvious outliers have been 
	removed from the data set; long-term precision: ~10%.


Anthropogenic VOCs:
14. "MTBE": Methyl-tertiary-butyl-ether, C5H12O; only quantified VOC of unequivocally 
	solely anthropogenic origin; retention time identified with authentic standard; 
	its FID response was estimated theoretically from comparison with isoprene; 
	mixing ratios should be viewed with some caution due to incomplete separation 
	from another, smaller anthropogenic compound, and acetaldehyde.

15. "toluene" (BPIN): anthropogenic, aromatic hydrocarbon, C7H8; occasional, very small 
	blank sample; no known chromatographic interferences; no indication of biogenic 
	sources as suggested by other authors; long-term precision: ~20%.



Standards (manufacturer's accuracy in parenthesis):
S1 (Scott-Marrin): acetaldehyde (±5%), MACR (±10%), heptane (±2%),
		a-pinene (±2%), acetone (±2%), isoprene (±2%)
	balance: nitrogen

S2 (Scott-Marrin): heptane, D-3-carene, a-pinene, d-limonene
		(unanalyzed Standard; a-pinene and heptane are consistent with S1).
	balance: nitrogen

MBO (Scott-Marrin): 2-methyl-3-buten-2-ol (±2%)
	balance: nitrogen

OVOC (Scott-Marrin; mixing ratios assigned by NCAR and highly uncertain for the 
	aldehydes and alcohols): butane, isoprene, acetaldehyde, acetone, butanal, 
	MACR, MEK, methanol, benzene, ethanol, pentanal, 2-pentanone, hexanal, n-butanol
	balance: nitrogen

BPIN (Scott Marrin): b-pinene (±2%), MACR (±2%), MBO (±2%), toluene (±2%),
 3-methyl-furan(±2%)
	balance: nitrogen