Geographical Properties of Ozone Concentrations in the Northeastern United States

Hourly, ground-level ozone measurements from 41 sites In eastern New York, northern New Jersey, Connecticut, and Massachusetts from May 1, 1974 to September 30, 1974 are analyzed. Nighttime concentrations, relative to those during the day, are highest in Massachusetts; more specifically, the ratio of the upper quartile of hourly average O3 concentrations at 1500 hours EST to the upper quartile at 0100 hours EST decreases with increasing distance from New York City, which is in the center of the tri-state urban complex (northern New Jersey, southwestern Connecticut and New York City). The site distributions of daily maximum concentrations are highest in the Stamford-Greenwich region of Connecticut and next highest in a region to the east and northeast of Stamford-Greenwich.