Challenge - Model

CHARACTERISTICS: Batch reactor 30 km above the Earth’s surface, T = 300ºK
SOFTWARE: Polymath 6.1 Educational Version (Windows Only)

This model uses the following equations (taken from Reactions) and reaction rates (from the NIST Kinetic Website). Notice that instead of starting with the concentration of CFCs in the stratosphere, we simply begin with an average concentration of chlorine that is present in the same space. Notice that the new NOx and Br mechanisms are included.

 

The only species present in our imaginary box are O₃, O₂, Cl, ClO, NO, NO₂, Br, and BrO. As a result, we need an initial concentration for each. Concentration data was taken from Brasseur and Soloman's Aeronomy of the Middle Atmosphere, in the units of molecules/cm³. Note that the concentrations of (ClO)₂, ClOO, O, and BrCl will tend to be zero at the beginning of our model. However, if we were to set the initial condition to '0' in Polymath, some of the differential equations would collapse. We suggest the use of an extremely small value of C_o = 1x10^-6 molecules/cm³ for those four substances.