BOUNDARY-LAYER OZONE VARIATIONS IN THE EASTERN UNITED-STATES AND THEIR ASSOCIATION WITH METEOROLOGICAL VARIATIONS - LONG-TERM VARIATIONS

Ten years (1981-1990) of Aerometric Information Retrieval System and Southern Oxidant Study ozone data and National Climatic Data Center meteorology data were used to establish statistics on summertime ozone in the eastern two-thirds of the United States (i.e., the region west of 100 W) and in the SOS region (i.e., the southeastern states), and to study the long-term variations of the ozone with surface climate parameters. The 10-year average summertime distribution of the surface ozone was oriented northeast-southwest with largest values in the northeast. Gradients extend east to west across the region as expected, but the strongest gradients were directed north-south and were found in the southern and northern part of the region. A region of high standard deviation (i.e., intersummer variations) was found extending from Indiana-Michigan eastward to the coast with a center (+/- 10 ppb) over New Jersey-Connecticut, and in the south, extending from Alabama eastward to the coast (+/- 8 ppb). The centers of large intersummer ozone variation were found in regions characterized by large numbers of anthropogenic sources (Clark, 1980) and by higher-than-normal surface temperatures. For the eastern United States, the area-averaged ozone anomalies ranged from approximately +6 ppb to approximately -2 ppb, with positive anomalies in the summers of 1983 and 1988 only. Highest correlations were noted between the ozone and surface temperature and sky comer, the weakest correlations, with surface pressure and surface winds. Positive surface temperature anomalies are not only indicators of areas where there is high intersummer ozone variability, but also of summers with higher-than-normal, area-averaged ozone.