Trichlorofluoromethane Transport in the Atmosphere.
Three dimensional CFC-11 distribution and transport are simulated by a Chemical Transport Model (CTM) with a T21 truncation and 32 vertical levels. The CFC-11 chemistry includes an explicit photodissociation package and a chemical reaction with O(^1D). The annual cycles of observational data in each semi-hemisphere are reasonably well reproduced by the simulations. The residual mass transport circulation predominately determines the distributions of the CFC-11 in the lower stratosphere. In the middle stratosphere, vertical residual circulation is balanced by the eddy mixing. The meridional residual transport is responsible for the mass exchanges not only between the tropical and extratropical regions but also between the polar and mid-latitude regions in the lower stratosphere. Above the lower stratosphere, the meridional residual transport has a maximum at lower latitudes, however the meridional eddy transport has the opposite direction at those latitudes and large enough to balance the residual transport there. Along the two sides of the polar night jet axis, the meridional eddy transport tends to move the mass away from the jet axis. The mass mixing across the polar night jet axis is not very effective until the polar vortex breaks up in the late spring. The GCM model provides similar forcing fields to the UKMO wind forcing data except for a weaker upward tropical motion.
- Pub Date:
- January 1995
- Physics: Atmospheric Science; Geophysics; Environmental Sciences