Open AccessChemical and meteorological characteristics associated with rapid increases of O 3 in Houston, Texas
Author(s) -
Berkowitz Carl M.,
Jobson Tom,
Jiang Guangfeng,
Spicer Chester W.,
Doskey Paul V.
Publication year - 2004
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2003jd004141
Subject(s) - isoprene , ozone , trace gas , environmental science , atmospheric sciences , meteorology , wind speed , tower , atmosphere (unit) , chemistry , physics , geography , organic chemistry , archaeology , copolymer , polymer
We report here on measurements made from the 62nd story of the Williams Tower on the west side of Houston, Texas between 15 August and 15 September 2000. The time series of trace gases differ from those at many other urban sites in having very rapidly increasing spikes of O 3 , HCHO, and PAN. Measurements show that the highest O 3 levels in Houston are not always those measured at the surface, and the extreme values may occur aloft. Plumes with high O 3 appear to be produced largely from local sources and to have the potential to form additional O 3 . The ozone production efficiency (7 molecules of O 3 produced per molecule of NO x consumed) when ΔO 3 /Δt ≥ 20 ppb per 15 min was found to be smaller than estimates made from observations directly downwind of the Ship Channel petrochemical plants (e.g., ∼12). Back trajectories show that simple straight line flow was associated with mean O 3 levels of 56 ppb, in contrast to flow patterns associated with a decrease in wind speed or flow reversal, which were associated with mean values of 63 ppb and extremes in excess of 125ppb. VOC samples taken during periods when ΔO 3 /Δt ≥ 20 ppb per 15 min were elevated and in particular light olefins were more than a factor of 7 greater than the corresponding samples collected on other occasions. No significant increase in isoprene at the Williams Tower was associated with these episodes. When air passed over stack emissions in eastern Houston, rich in VOCs, a Lagrangian model simulated O 3 production rates of ∼50 ppb hr −1 .