Pollutant Transport During a Regional O 3 Episode in the Mid-Atlantic States

• Published in: Journal of the Air & Waste Management Association (1995) 1998-09, Vol.48 (9), p.786-797
• Main Authors: Ryan, William F, Doddridge, Bruce G, Dickerson, Russell R, Morales, Raymond M, Hallock, Kristen A, Roberts, Paul T, Blumenthal, Donald L, Anderson, Jerry A, Civerolo, Kevin L
• Format: Article
• Language: English
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.1998.10463737

Ozone (O ) concentrations in the Baltimore-Washington (B-W) metropolitan area frequently exceed the National Ambient Air Quality Standard (NAAQS) in the summer months. The most extreme O events occur in multi-day high O episodes. These events can be regional in scale, with O concentrations exceeding the NAAQS at numerous locations along the eastern U.S. seaboard, and are typically associated with slow-moving or stagnant high pressure systems. In the B-W region, the most extreme events typically occur with surface high pressure overhead or just west of the region and an upper air high-pressure area (ridge) to the west or northwest. Besides providing conditions conducive to local O production (subsidence and strong low-level inversions, weak horizontal winds, little cloud cover), this weather pattern may also result in transport of O and its precursors from heavily industrialized areas west and north of the B-W region. In this paper, observations and back trajectories made during the severe regional O event of July 12-15, 1995, are used to confirm the hypothesis that significant regional-scale transport of O and its precursors occur during extreme O events of the standard type in the B-W area.