^{1}

^{1}

A scaling analysis has been used to capture the integrated behaviour of several photochemical mechanisms for a wide range of precursor concentrations and a variety of environmental conditions. The Buckingham Pi method of dimensional analysis was used to express the relevant variables in terms of dimensionless groups. These grouping show maximum ozone, initial NO<sub>x</sub> and initial VOC concentrations are made non-dimensional by the average NO<sub>2</sub> photolysis rate (<i>j<sub>av</sub></i>) and the rate constant for the NO–O<sub>3</sub> titration reaction (<i>k</i><sub>NO</sub>); temperature by the NO–O<sub>3</sub> activation energy (<i>E</i><sub>NO</sub>) and Boltzmann constant (<i>k</i>) and total irradiation time by the cumulative <i>j<sub>av</sub></i>Δ<i>t</i> photolysis rate. The analysis shows dimensionless maximum ozone concentration can be described by a product of powers of dimensionless initial NO<sub>x</sub> concentration, dimensionless temperature, and a similarity curve directly dependent on the ratio of initial VOC to NO<sub>x</sub> concentration and implicitly dependent on the cumulative NO<sub>2</sub> photolysis rate. When Weibull transformed, the similarity relationship shows a scaling break with dimensionless model output clustering onto two straight line segments, parameterized using four variables: two describing the slopes of the line segments and two giving the location of their intersection. A fifth parameter is used to normalize the model output. The scaling analysis, similarity curve and parameterization appear to be independent of the details of the chemical mechanism, hold for a variety of VOC species and mixtures and a wide range of temperatures and actinic fluxes.

_{2}O

_{2}and HNO

_{3}as indicators for ozone-NOx-hydrocarbon sensitivity in urban locations, J. Geophys. Res., 100, 14 175–14 188, 1995. ]]>