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 S outhern Oxidant Study ozone data and National Climatic Data Center met eorology 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 param eters. The 10-year average summertime distribution of the surface ozon e was oriented northeast-southwest with largest values in the northeas t. Gradients extend east to west across the region as expected, but th e strongest gradients were directed north-south and were found in the southern and northern part of the region. A region of high standard de viation (i.e., intersummer variations) was found extending from Indian a-Michigan eastward to the coast with a center (+/- 10 ppb) over New J ersey-Connecticut, and in the south, extending from Alabama eastward t o the coast (+/- 8 ppb). The centers of large intersummer ozone variat ion were found in regions characterized by large numbers of anthropoge nic sources (Clark, 1980) and by higher-than-normal surface temperatur es. For the eastern United States, the area-averaged ozone anomalies r anged 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, th e weakest correlations, with surface pressure and surface winds. Posit ive surface temperature anomalies are not only indicators of areas whe re there is high intersummer ozone variability, but also of summers wi th higher-than-normal, area-averaged ozone.