The inability of tropical lower stratospheric ozone to recover in a chemistry-radiation-dynamics model

The Inability of Tropical Lower Stratospheric Ozone to Recover in a Chemistry-Radiation-Dynamics Model

Long-term time dependent simulations out to the year 2050 using the GSFC interactive 2D chemistry-radiation-dynamics model predict that the ozone depletion in the tropical lower stratosphere will not recover. The model runs incorporate changing CFCs, methane, nitrous oxide, carbon dioxide, and heterogeneous chemistry on sulfate aerosols. With only background aerosol amounts, tropical ozone at 50 hPa is reduced by ~2% between 1980 and 2000 and remains at that level of depletion out to 2050. With the addition of the Pinatubo aerosol perturbation, the ozone in 1992 is reduced by ~6% from 1980 values and recovers to a depletion of 2% in 1996. This 2% depletion remains out to 2050. These results depend on the inclusion of both heterogeneous chemistry on aerosol surfaces and increasing carbon dioxide. The sustained depletion is caused by a complicated interplay between chemical production and dynamics.