Figure 14.2a sn The combined distribution, represented by the me, masks the contributions of the individual modes, shown by dashed lines and does not show the nature of The more

or less straight-line portion of the distribution between 0.1 and 10 μm can be represented by an inverse power law distribution (the Junge distribution) the surface or mass distributions. For the data shown in Figure 14.2a, AN A log(d,) = 24.0d-3.08 for d in um. Equation 14.1 is empirical; there is no fundamental or theoretical rea- son that the atmospheric aerosol should have this distribution function. Mode Nuclei Accumulation Coarse Particle Data from Whitby (1978). Figure 14.2b presents the urban aerosol size distribution as cumulative number and volume distributions on a log-probability graph. (See Section 4.5.) The distri butions show significant departures from a lognormal distribution, and the contri- butions of the individual modes are hidden. Figures 14.2c and 14.2d respectively show particle number and volume per unit log interval on an arithmetic scale ver- TABLE 14.3 Modal parameters for average urban aerosol.ª CMD CN (µm) (cm-³) 0.014 0.054 0.86 GSD 1.80 2.16 2.21 106,000 32,000 5.4 (14.1) Cvol (µm³/cm³) 0.63 38.4 30.8 sites for the cataly thropogenic chlorofluorocarbons (r to atomic chlorine (CI), which reacts with ozone (O3) to form oxygen (O₂) and chlo rous acid (HOCI). In the polar spring, the sun photodissociates these compounds keeps repeating with the continued destruction of ozone. Volcanic eruptions enhance this process by increasing the stratospheric aerosol, which migrates to the poles and provides additional surface for the catalytic activation of chlorine. See Seinfeld and Pandis (1998). PROBLEMS 14.1 For the modal data given in Table 14.3, what is the particle number per unit mass for each mode? Assume standard particle density. Nyeki, distrib 5211- Puesche 383- Schwar Ant SMIC, MI Sienfe Whit (1