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OZONE OVER SAN FRANCISCO. MEANS AND PATTERNS DURING POLLUTION EPISODES
Citation:
MacKay, K. OZONE OVER SAN FRANCISCO. MEANS AND PATTERNS DURING POLLUTION EPISODES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/4-77/046.
Description:
Measurements of meteorological parameters were taken at six levels and ozone at four levels between 260m and 473m ASL on the Mt. Sutro T.V. Tower in San Francisco during the summers of 1974 through 1976. Hourly average ozone concentrations within the elevated inversion layer at this location exceeded the 8 pphm (160 microgram/cu m) National Ambient Air Quality Standards about 15% of the time. High inversion layer ozone concentrations at this site were associated with high surface concentrations occurring during area-wide air pollution episodes. These episodes occurred when a lobe of the Pacific high pressure system penetrated inland. During these episodes, superposition of synoptic scale northeasterly flow and locally produced mesoscale flow caused easterly or light westerly flows during the late forenoon within the inversion layer and westerly flow in the late afternoon. Inland, where the inversion was destroyed from below, inversion layer and surface generated pollutants were convectively mixed. This mixing and the wind oscillation recycled pollutants. The episodes ended when the synoptic situation reverted to one more normal for the season and pollutants were advected from the area.