Relationships between regional ozone pollution and emissions of nitrogen oxides in the eastern United States

This study examines the relationships between regional ozone (O 3 ) pollution and emissions of nitrogen oxides (NO x ) in the eastern United States during summer. Using measurements from rural sites during the summer of 1995, three 4‐day time periods are identified during which significant enhancements of surface O 3 occurred on spatial scales ranging from 0.5 to 1.8 million km 2 . Each of these episodes was characterized by relatively stagnant meteorological conditions conducive to the photochemical formation and accumulation of O 3 in the boundary layer. The surface ozone accumulation efficiency (SOAE), a parameter which relates the O 3 accumulation to the NO x emission density in a given region, is estimated to range from 1 to 2 ppbv O 3 kg −1 N km −2 in the eastern United States during summer. This result is discussed in the context of regional NO x ‐based O 3 control strategies. In addition, the net ozone production efficiency (OPE) is estimated to range from 2 to 3 ppbv O 3 ppbv −1 NO x in this region.