Anthropogenic emissions from urban sprawl, traffic, and industrialization along the northeast corridor of the United States should have an increasingly profound effect on urban and regional air quality. Surface air quality over populated areas is an important issue given persuasive data linking high levels of atmospheric oxidants and particulate matter to deleterious human health effects.

Predictions of air quality episodes along the Northeast corridor can be confounded by the frequent occurrence of local and regional scale circulations that can influence the magnitude, timing, and spatial extent of air pollution events. While there may be good understanding of the synoptic scale patterns associated with severe air pollution episodes in the mid-Atlantic region, local and regional gradients generated by land-sea discontinuities, topographic features, urban environments, and complicated by a convoluted coastline can give rise to sub-synoptic circulations that are difficult to predict. Forecast skill is often compromised due to the complex scale interactions between the surface layer, boundary layer, and free troposphere. An improved understanding of the influence of local and regional circulations on sources, sinks, transport, mixing, and photochemical transformations controlling the observed abundances of photochemical oxidants and fine particle haze over the mid-Atlantic region is key to developing any capability in the future to forecast such pollution events reliably.

During the summers of 1999, 2001, and 2002 investigators from several institutions and government laboratories conducted an intensive field campaign about 18 km ENE of Philadelphia (40.04o N, 75.00o W). The objectives of this project were to investigate the conditions within the urban polluted environment to find relationships between the meteorological conditions and high O3 concentrations, increased levels of PM2.5, and contributions from local and distant sources. Following on the summer campaign, Millersville conducted a local study of particulate matter in the wintertime boundary layer in January-February 2004. These investigations made apparent the influence that sub-synoptic scale circulations have on the variability of trace gas and particle concentrations. This talk presents in-situ meteorological observations of select meteorological events and their influence on the trace gas and fine particle concentrations.

Richard D. Clark is the Chair of the Department of Earth Sciences and Professor of Meteorology at Millersville University of Pennsylvania. His research interests are boundary layers and turbulence, air chemistry, and science education. He has a Ph.D. in atmospheric science from the University of Wyoming and is a member of the American Meteorological Society and the American Geophysical Union. Contact him at Richard.Clark@millersville.edu