A scaling analysis of ozone photochemistry

[摘要] A scaling analysis has been used to capture the integrated behaviour ofseveral photochemical mechanisms for a widerange of precursor concentrations and a variety of environmentalconditions.The Buckingham Pi method of dimensional analysis was usedto express the relevant variables in terms of dimensionless groups.These grouping show maximum ozone,initial NO_x and initial VOC concentrations are made non-dimensionalby the average NO₂ photolysis rate (j_av) and the rateconstant for the NO–O₃ titration reaction (k_NO);temperature by the NO–O₃ activation energy (E_NO)and Boltzmann constant (k) and total irradiation time by the cumulativej_avΔt photolysis rate. The analysis showsdimensionless maximum ozone concentration can be described by aproduct of powers of dimensionless initial NO_x concentration,dimensionless temperature, and a similarity curvedirectly dependent on the ratio of initial VOC to NO_x concentrationand implicitly dependent on the cumulative NO₂ photolysisrate.When Weibull transformed, the similarity relationship shows a scalingbreak with dimensionless model output clustering onto two straightline segments, parameterized using four variables: two describing theslopes of the line segments and two giving the location of theirintersection. A fifth parameter is used to normalizethe model output. The scaling analysis, similarity curve andparameterization appear to be independent of the details of thechemical mechanism, hold for a variety of VOC species and mixtures anda wide range of temperatures and actinic fluxes.

[学科分类] 大气科学