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4th largest urban population in the U.S., much of which commutes from remote suburbs, results in broad NOx emissions throughout the Houston–Galveston–Brazoria Region (HGBR, note that Brazoria County is adjacent to Houston and Galveston). 2) One of the largest petrochemical production sectors in the world often produces range transport of O3 and precursors from remote locations can exacerbate local pollution levels (e.g., Pierce et al., 2009). Past efforts to predict O3 exceedances in Houston were hampered by the lack of information on the O3 profile and the extent of vertical mixing (Davis and Speckman, 1999). From July 2004–June 2008, more than 220 ozonesondes were launched from Rice University or the University of Houston (Rice and UH respec