I. Data set hcwin00.v1: General: This data set contains mixing ratios of biogenic and anthropogenic volatile organic compounds and CO measured between October 31 and March 28, 2001. All values are reported in ppb. The used chromatographic columns were A: PLOT-Alumina from J&W, and B: RTX-Wax from Restek. 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. Calibration was carried out against one or more diluted ppm-Standards as described below, or via neohexane as an internal standard on the PLOT-Alumina column. The latter response factor stability was assessed to 0.03 ppb/area with a 99% confidence level of 3%, and a detection limit of ~5 ppt at a sample size of 450 mL (note: sample size on B-channel was only 150-300 mL). All mixing ratio data are from the top of the tower. Some very high and very low mixing ratios that were identified as outliers have been set "NA". All samples containing standard additions have been removed. The microtraps were not changed during the measurement period. Note: All chromatograms on channel B 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 was calculated from the calibration curve determination coefficient, r2; background on calibrations was removed by interpolating between the measurements before and after the calibration) 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. Hydrocarbons, alkanes: 3. "propane": C3H8; although breakthrough of this high volatility hydrocarbon cannot be excluded, at its natural abundance, breakthrough was probably small and we kept it in the dataset as it scales well with the other hydrocarbons (Note: breakthrough was assessed via adding hydrocarbon mixtures to the main air stream, comparing this direct calibration with the indiret one via the internal standard) 4. "butane": C4H10; shortest hydrocarbon for which no breakthrough was detected 5. "isobutane" = 2-methyl-propane; C4H10 6. "pentane": C5H12 7. "isopentane" = 2-methyl-butane: C5H12 8. "hexane": C6H14 9. "2-methyl-pentane": C6H14 10. "3-methyl-pentane": C6H14 alkenes 11. "1-butene": C4H8; shortest alkene without breakthrough, and unaffected by contamination 12. "1-pentene": C5H10 alkines 13. "acetylene": C2H2; although breakthrough is obvious for this hydrocarbon, we left it in the dataset as an indicator of anthropogenic pollution 14. "propyne": C3H4 others on the PLOT column 15. "MTBE+": a hydrocarbon identified as 2-methyl-propene (C4H8), which is produced from MTBE via methanol elimination either in the Nafion Dryer or later during the thermal desorption; a contamination with another hydrocarbon acannot be excluded 16. "benzeneA": C6H6; benzene on the PLOT column 17. "tolueneA": C7H8; toluene on the PLOT column; the hydrocarbon with the longest retention; comparison with the WAX column data suggests that a 10% loss occurs inside the column 18. "toluene": toluene on the WAX column; comparisons with the PLOT column results show a consistent measurement 19. "carbon monoxide": CO; measurements from the Molsieve 5A column on our CO setup; Note that these data may not be completely accurate due to issues with the CO calibration standard setup Isoprene and its oxidation products: 20. "isoprene" (S1, OVOC): C5H8, biogenic VOC; among the most precisely measured compounds; stable response throughout the whole data set; long-term precision: 3%. 21. "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). 22. "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: 3% 23. "isoprene+MBO": sum of isoprene and converted MBO to isoprene on the PLOT column; a comparison with the WAX column data shows consistency Oxygenated VOCs: 24. "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 NOT corrected for the coeluting compound methyl-ethyl-ketone; varying occurrence in blank samples; long-term precision: ~30% (assuming a constant response factor for MEK in the same standard). 25. "ethanol" (OVOC): C2H5OH, partially coeluting with benzene; mixing ratios were calculated using the benzene to toluene ratio from the PLOT column to substract benzene from the sum peak of ethanol and benzene; small and varying occurrence in blank samples. No consistent calibration. 26. "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: 2% 27. "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: ~5%. 28. "MBO" (MBO, BPIN): Methylbutenol, C5H9OH, dominant local emission compound from ponderosa pine; most abundant reactive hydrocarbon; long-term precision: 5%. Monoterpenes (Note: all monoterpenes, but in particular 3-carene and limonene, show breakthrough characteristics at higher (>2-3 ppb) mixing ratios): 29. "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: ~2%. 30. "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; consistency with alpha-pinene assures us that these measurements are reasonable; long-term precision: ~30%. 31. "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%. 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