HR: 08:00h
AN: A51G-01    [Abstracts]
TI: The Role of Galveston Bay Meteorology in Ozone Concentrations in Houston, Texas
AU: * Nielsen-Gammon, J W
EM: n-g@tamu.edu
AF: Texas A&M University, Dept. of Atmospheric Sciences 3150 TAMUS, College Station, TX 77807, United States
AU: Tobin, J
EM: jtobin@tamu.edu
AF: Texas A&M University, Dept. of Atmospheric Sciences 3150 TAMUS, College Station, TX 77807, United States
AB: Galveston Bay is a body of water approximately 50 km by 30 km that opens into the Gulf of Mexico. The head of Galveston Bay is adjacent to the Houston Ship Channel, where large industrial emitters of ozone precursors are located. We consider the role of coastal circulations and mixing suppression over Galveston Bay in the location and magnitude of peak 8-h ozone values at monitors within the Houston-Galveston-Brazoria nonattainment area. Galveston Bay is found to have a salutary effect on ozone concentrations under most circumstances. Aside from boats and ships, Galveston Bay is free of ozone precursor emissions, and the onset of the sea breeze along Galveston Bay usually causes an immediate drop in ozone levels. The situation changes dramatically when the morning wind direction is from the northwest, allowing ozone precursors emitted during the night or early morning that are distributed in a shallow atmospheric layer to be carried over Galveston Bay. In morning and early afternoon, mixing is suppressed over Galveston Bay, and precursor concentrations remain high in the absence of ventilation. If winds are strong, high ozone concentrations are generally observed along the far shore of Galveston Bay. If winds are weak, a sea breeze will develop along Galveston Bay, and high levels of ozone will be carried back onshore in the vicinity of the Ship Channel. The coastal oscillation (a regular rotation of the wind vector driving by coastal heating contrasts near 30 N) can lead to wind reversals and high values of ozone by itself. We investigate peak ozone concentrations under a variety of wind conditions to infer whether the ozone concentrations are, on balance, higher due to the net effect of meteorological processes associated with Galveston Bay.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 3307 Boundary layer processes
DE: 3329 Mesoscale meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting