Stratospheric dynamical response and ozone feedbacks in the presence of SO2 injections

The quasi-biennial oscillation (QBO) of the tropical zonal wind is altered by the various sulfur dioxide injections. In a simulation with a 12Tgyr(-1) equatorial injection, and with fully interactive chemistry, the QBO period lengthens to approximate to 3.5years but never completely disappears. However, in a simulation with specified (or noninteractive) chemical fields, including O-3 and prescribed aerosols taken from the interactive simulation, the oscillation is virtually lost.

In addition, we find that geoengineering does not always lengthen the QBO. We further demonstrate that the QBO period changes from 24 to 12-17months in simulations with sulfur dioxide injections placed poleward of the equator. Our study points to the importance of understanding and verifying of the complex interactions between aerosols, atmospheric dynamics, and atmospheric chemistry as well as understanding the effects of sulfur dioxide injections placed away from the Equator on the QBO.