TY - JOUR
T1 - Deciphering the role of radical precursors during the second Texas air quality study
AU - Olaguer, Eduardo P.
AU - Rappenglück, Bernhard
AU - Lefer, Barry
AU - Stutz, Jochen
AU - Dibb, Jack
AU - Griffin, Robert
AU - Brune, William H.
AU - Shauck, Maxwell
AU - Buhr, Martin
AU - Jeffries, Harvey
AU - Vizuete, William
AU - Pinto, Joseph P.
N1 - Funding Information:
The Aztec flew a total of 50 hr for TERC, mostly in the Houston region but also in the vicinity of a stationary front near the DFW area during an O3 exceedance. In addition, the aircraft was deployed outside Houston and Dallas to investigate long-range transport of pollution. This latter experiment was funded by the Northeast Texas Air Care group of stakeholders.
PY - 2009/11
Y1 - 2009/11
N2 - The Texas Environmental Research Consortium (TERC) funded significant components of the Second Texas Air Quality Study (TexAQS II), including the TexAQS II Radical and Aerosol Measurement Project (TRAMP) and instrumented flights by a Piper Aztec aircraft. These experiments called attention to the role of short-lived radical sources such as formaldehyde (HCHO) and nitrous acid (HONO) in increasing ozone productivity. TRAMP instruments recorded daytime HCHO pulses as large as 32 parts per billion (ppb) originating from upwind industrial activities in the Houston Ship Channel, where in situ surface monitors detected HCHO peaks as large as 52 ppb. Moreover, Ship Channel petrochemical flares were observed to produce plumes of apparent primary HCHO. In one such combustion plume that was depleted of ozone by large emissions of oxides of nitrogen (NOx), the Piper Aztec measured a ratio of HCHO to carbon monoxide (CO) 3 times that of mobile sources. HCHO from uncounted primary sources or ozonolysis of underestimated olefin emissions could significantly increase ozone productivity in Houston beyond previous expectations. Simulations with the CAMx model show that additional emissions of HCHO from industrial flares or mobile sources can increase peak ozone in Houston by up to 30 ppb. Other findings from TexAQS II include significant concentrations of HONO throughout the day, well in excess of current air quality model predictions, with large nocturnal vertical gradients indicating a surface or near-surface source of HONO, and large concentrations of nighttime radicals (∼30 parts per trillion [ppt] HO2). HONO may be formed heterogeneously on urban canopy or particulate matter surfaces and may be enhanced by organic aerosol of industrial or motor vehicular origin, such as through conversion of nitric acid (HNO3). Additional HONO sources may increase daytime ozone by more than 10 ppb. Improving the representation of primary and secondary HCHO and HONO in air quality models could enhance the simulated effectiveness of control strategies.
AB - The Texas Environmental Research Consortium (TERC) funded significant components of the Second Texas Air Quality Study (TexAQS II), including the TexAQS II Radical and Aerosol Measurement Project (TRAMP) and instrumented flights by a Piper Aztec aircraft. These experiments called attention to the role of short-lived radical sources such as formaldehyde (HCHO) and nitrous acid (HONO) in increasing ozone productivity. TRAMP instruments recorded daytime HCHO pulses as large as 32 parts per billion (ppb) originating from upwind industrial activities in the Houston Ship Channel, where in situ surface monitors detected HCHO peaks as large as 52 ppb. Moreover, Ship Channel petrochemical flares were observed to produce plumes of apparent primary HCHO. In one such combustion plume that was depleted of ozone by large emissions of oxides of nitrogen (NOx), the Piper Aztec measured a ratio of HCHO to carbon monoxide (CO) 3 times that of mobile sources. HCHO from uncounted primary sources or ozonolysis of underestimated olefin emissions could significantly increase ozone productivity in Houston beyond previous expectations. Simulations with the CAMx model show that additional emissions of HCHO from industrial flares or mobile sources can increase peak ozone in Houston by up to 30 ppb. Other findings from TexAQS II include significant concentrations of HONO throughout the day, well in excess of current air quality model predictions, with large nocturnal vertical gradients indicating a surface or near-surface source of HONO, and large concentrations of nighttime radicals (∼30 parts per trillion [ppt] HO2). HONO may be formed heterogeneously on urban canopy or particulate matter surfaces and may be enhanced by organic aerosol of industrial or motor vehicular origin, such as through conversion of nitric acid (HNO3). Additional HONO sources may increase daytime ozone by more than 10 ppb. Improving the representation of primary and secondary HCHO and HONO in air quality models could enhance the simulated effectiveness of control strategies.
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U2 - 10.3155/1047-3289.59.11.1258
DO - 10.3155/1047-3289.59.11.1258
M3 - Article
C2 - 19947108
AN - SCOPUS:73349089961
SN - 1096-2247
VL - 59
SP - 1258
EP - 1277
JO - Journal of the Air and Waste Management Association
JF - Journal of the Air and Waste Management Association
IS - 11
ER -
