Coupling the vertical distribution of ozone in the atmospheric boundary layer

Vertical measurements of ozone were made on a 610 m tall tower located about 15 km southeast of Raleigh, NC, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area and other metropolitan areas in the state. Ozone was monitored at 10, 250, and 433 m height levels during the summer months of 1993-1995 and at 10, 76, 128, and 433 m height levels during the summer months of 1996-1997. A regional atmospheric chemistry/transport model, called Multiscale Air Quality Simulation Platform (MAQSIP), was also employed to simulate three-dimensional O-3 distribution over the eastern United States for a 2-month period (June 1-July 31, 1995). Through complementary analyses of the 5-year data and the modeling results, this paper examines the vertical distribution of ozone concentrations in the atmospheric boundary layer with the emphasis on the contribution of residual ozone aloft to the ground level ozone enhancement during the daytimes. Both the observation and the model results show a strong correlation between the nighttime and early morning ozone concentrations ((C) over bar(R)) in the residual layer above the nocturnal boundary layer (NBL) and the maximum ground level concentration ((C) over bar(omax)) the following afternoon. On the basis of this correlation, an observational model for maximum ozone (C) over bar(omax) = 27.67 exp(0.016 (C) over bar(R)) is proposed, where concentrations are expressed in parts per billion by volume (ppbv). Model results indicate, however, that both the coefficient representing the regional background ozone concentration and the exponent in the above relationship may vary considerably over the eastern United States.