High ozone events and attainment demonstrations in Houston, Texas.

摘要

The Houston-Galveston-Brazoria area has had multiple decades of persistent high ozone (O3) values. We have analyzed ten years of ground-level measurements at 25 monitors in Houston and found that peak 1-h O3 concentrations were often associated with large hourly O 3 increases. A non-typical O3 change (NTOC) --- defined here as an increase of at least 40 ppb/hr or 60 ppb/2hrs --- was measured 25% of the time when concentrations recorded at a monitor exceeded the 8-h O3 standard. CAMx model simulations were found to be limited in their ability to simulate NTOCs, under predicted maximum observed rates of O3 increases by more than 50 ppb/hr, and had difficulty simulating spatially isolated, high O3 events measured at monitors that routinely violate the 8-h O3 standard. Our results suggest that this modeling system will be unable to guide the selection of effective control strategies required to meet a more stringent federal 8-h O3 standard.