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Abstract

Sulfur dioxide can be injected directly into the stratosphere during and after explosive tropical volcanic eruptions. There, it mostly converts to sulfate aerosol leading to a warming of the lower stratosphere that can alter the stratospheric circulation. The impact of such events on the stratosphere is well known, but the response of the mesosphere is less understood. Few observations after the 1991 Pinatubo eruption indicate a post-volcanic mesospheric warming. The underlying dynamical mechanism behind such a phenomenon was investigated by us using the UA-ICON model. We simulated the response of the middle atmosphere to a tropical eruption that emitted twice as much sulfur dioxide as was released by the 1991 Pinatubo event. Our study found a significant warming of the polar summer mesopause of up to 15-21 K in the first austral summer after the simulated eruption. We argue that this mesospheric temperature perturbation is mainly due to vertical coupling in the summer hemisphere and potentially enhanced by interhemispheric coupling.