Characterization of biogenic volatile organic compounds and meteorology at Azusa during the SCOS97-NARSTO
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- 作者：Reissell ; Anni ; MacDonald ; Clinton ; Roberts ; Paul ; Arey ; Janet
- 关键词：Biogenic volatile organic compounds ; Meteorological modeling ; Monoterpenes ; Isoprene
- 刊名：Atmospheric Environment
- 出版年：2003
- 出版时间：2003
- 年：2003
- 卷：37
- 期：Supplement 2
- 页码：181-196
- 全文大小：494 K
文摘
Meteorological modeling and analyses were performed for the 4–6 August and 4–6 September 1997 intensive sampling episodes of the 1997 Southern California Ozone Study (SCOS97-NARSTO). This investigation was conducted to study the connection of measured and modeled meteorological phenomenon with measured biogenic volatile organic compound (BVOC) concentrations. Trajectory and surface wind analysis for five out of the six intensive sampling days indicated that drainage flow from the mountains at nighttime and early morning affected the BVOCs measured at the Azusa, CA monitoring site. Nitric oxide emissions from vehicles precluded nighttime chemical reactions of the BVOCs at Azusa, allowing overnight accumulation of local monoterpene emissions in addition to monoterpenes transported by drainage flows. The monoterpene mixing ratios maximized in the early morning hours and the monoterpene/CO ratios showed sharp maxima at 0300–0600h PDT on all days. In contrast, normalization of benzene to CO diminished its diurnal variation, consistent with vehicle traffic as the source for these two long-lived anthropogenic compounds. Substantial early morning methacrolein (MACR) and methyl vinyl ketone (MVK) mixing ratios (and high (MACR + MVK)/isoprene ratios) measured at Azusa on all episode days were consistent with drainage flow from elevated sites which had received NOx emissions and ozone transported from the urban basin by daytime upslope flows. Isolation of these elevated sites from the basin NO emissions as the nocturnal boundary layer was established would allow rapid nighttime nitrate radical reaction with isoprene, or slower isoprene reaction with ozone, to produce high (MACR + MVK)/isoprene ratios in drainage flows into Azusa.