Houston, Texas - Urban air quality studies

Urban zones represent areas in which significant amounts of gaseous pollutants and particulate matter are released into the atmosphere. The Houston-Galveston Brazoria Area (HGB), located close to the Gulf of Mexico, is the fourth largest metropolitan area in the United States. 
The University of Houston (UH) set up an air quality measurement facility at the University main campus on the roof of the 18-story tall North Moody Tower residence hall. The general information about this site is given in Table 1. This facility includes a 35 ft high sampling tower and is equipped with air chemistry measurements including O3, CO, NO, NO2, NO, PAN, PPN, MPAN, VOCs, and meteorological instrumentation. It also includes measurements of photolysis frequencies for O3, NO, HONO and HCHO and 16 other important photolysis reactions.
Aero-Laser equipment is used for the TexAQS II Radical Measurement Project (TRAMP) in 2006 and several other research programs.

Moody Progress Report

Further informations

Publications

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Article

Title: Formaldehyde columns from the Ozone Monitoring Instrument: Urban versus background levels and evaluation using aircraft data and a global model
Authors: N.L. Boeke, J.D. Marshall, S. Alvarez, K.V. Chance, A. Fried, T.P. Kurosu, B. Rappenglück, D. Richter, J. Walega, P. Weibring and D.B. Millet
Journal: J. Geophys. Res.
Year: 2011
Volume: 116
Pages: D05303
DOI: 10.1029/2010JD014870
Web URL: http://www.agu.org/pubs/crossref/2011/2010JD014870.shtml
Abstract: We combine aircraft measurements (Second Texas Air Quality Study, Megacity Initiative: Local and Global Research Observations, Intercontinental Chemical Transport Experiment: Phase B) over the United States, Mexico, and the Pacific with a 3-D model (GEOS-Chem) to evaluate formaldehyde column (ΩHCHO) retrievals from the Ozone Monitoring Instrument (OMI) and assess the information they provide on HCHO across local to regional scales and urban to background regimes. OMI ΩHCHO correlates well with columns derived from aircraft measurements and GEOS-Chem (R = 0.80). For the full data ensemble, OMI's mean bias is −3% relative to aircraft-derived ΩHCHO (−17% where ΩHCHO> 5 × 1015 molecules cm−2) and −8% relative to GEOS-Chem, within expected uncertainty for the retrieval. Some negative bias is expected for the satellite and model, given the plume sampling of many flights and averaging over the satellite and model footprints. Major axis regression for OMI versus aircraft and model columns yields slopes (95% confidence intervals) of 0.80 (0.62–1.03) and 0.98 (0.73–1.35), respectively, with no significant intercept. Aircraft measurements indicate that the normalized vertical HCHO distribution, required by the satellite retrieval, is well captured by GEOS-Chem, except near Mexico City. Using measured HCHO profiles in the retrieval algorithm does not improve satellite-aircraft agreement, suggesting that use of a global model to specify shape factors does not substantially degrade retrievals over polluted areas. While the OMI measurements show that biogenic volatile organic compounds dominate intra-annual and regional ΩHCHO variability across the United States, smaller anthropogenic ΩHCHO gradients are detectable at finer spatial scales (∼20–200 km) near many urban areas.

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