transport coefficients and the winds above 60 km are quite uncertain. According to Ebel (14) substantial variations of Kuy and Kzz are expected to occur with latitude, altitude, and season. Therefore the values of (KyuKzz)i used to make the predictions should be regarded as order-of-magnitude estimates. A further, more fundamental uncertainty in the present analysis occurs because the K-theory of Reed and German (10) is not always adequate to simulate the motion of tracers in the atmosphere (17). In particular, the transport in the upper stratosphere and mesosphere is dominated by strong season-dependent winds. The circulation patterns are characterized by wave numbers of 0, 1, and 2. During the summer, the winds are easterly and spiral outward from the pole. This flow pattern is shown in Fig. 9.6 of Danielsen and Louis (18). Calculations by Shoeberl and Strobel (7), and by Holton and Wehrbein (8) predict zonally averaged meridional wind speeds of 1 to 2 m/s rather than the 0.3 m/s assumed here. In regions where v > KyvlL (—0.3 m/s for altitudes above 60 km), Eq. 8 should be used rather than Eq. 9. Under these circumstances, the pollutants will be injected at one latitude and will then slowly spiral toward the equator. The profile of the concentration at constant altitude versus latitude can no longer be represented as Gaussian-like with a pronounced maximum such as that shown as curve a in Fig. 8. Instead, the profile will more nearly resemble curve b of Fig. 8. For curve b, a corridor effect will be considered to exist when the meridional gradient of the abundance is sufficient to produce a 20% change in the abundance over a length L. In the winter, the circulation pattern is reversed and the winds are westerly and
RkJQdWJsaXNoZXIy MTU5NjU0Mg==