Comparison of stratospheric ozone destruction by fluorocarbons 11, 12, 21, and 22

摘要

Measured photoabsorption cross sections for fluorocarbons (FC) 11, 12, 21, and 22 are presented for the wavelength region from 1740Å to about 2200Å. Solar radiation in this region dissociates these molecules in the stratosphere releasing atomic chlorine which participates in catalytic reactions that destroy ozone. Photolysis by solar UV is the only known loss mechanism for FC11 and FC12. However, FC21, and FC22 also react with OH in the troposphere reducing the amount of ground level releases which reach the stratosphere. Calculations comparing the steady state stratospheric ClX due to equal release rates of fluorocarbons 11, 12, 21, and 22 are presented using a range of OH profiles and eddy diffusion coefficients. These calculations indicate approximately a factor of 20 to 450 less ClX in the stratosphere for FC21 and a factor of 40 to 130 for FC22, compared to an equal release rate of FC11 and FC1