Impact of the latitude of stratospheric aerosol injection on the Southern Annular Mode | CU Experts

The impacts of Stratospheric Aerosol Injection strategies on the; Southern Annular Mode (SAM) are analysed with the Community Earth System; Model (CESM). Using a set of simulations with fixed single-point SO2; injections we demonstrate the first-order dependence of the SAM response; on the latitude of injection, with the northern hemispheric and; equatorial injections driving a response corresponding to a positive; phase of SAM and the southern hemispheric injections driving a negative; phase of SAM. We further demonstrate that the results can to first order; explain the differences in the SAM responses diagnosed from the two; recent large ensembles of geoengineering simulations utilising more; complex injection strategies - GLENS and ARISE-SAI - as driven by the; differences in the simulated sulfate aerosol distributions. Our results; point to the meridional extent of aerosol-induced lower stratospheric; heating as an important driver of the sensitivity of the SAM response to; the injection location.

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