PNNL

Abstract

Injections of sulfur dioxide into the stratosphere are among several proposed methods of solar radiation management. Such injections cool the earth’s climate. However, they significantly alter the dynamics of the stratosphere. We explore here the stratospheric dynamical response to sulfur dioxide injections ~ 5 km above the tropopause at multiple latitudes (equator, 15?S, 15?N, 30?S and 30?N) using a fully coupled earth system model, Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM1(WACCM)). We find that in all simulations, the tropical lower stratosphere warms primarily between 30?S and 30?N, regardless of injection latitude, due to a combination of radiative and dynamical heating, as well as changes in ozone concentrations. The quasi-biennial oscillation (QBO) of the tropical zonal wind is altered by the various sulfur dioxide injections. In a simulation with a 12 Tg yr-1 equatorial injection, and with fully interactive chemistry, the QBO period lengthens to ~ 3.5 years, and it remains in a persistent westerly phase with the same injection. However, in a simulation with specified (or non-interactive) chemical fields, including O3 and prescribed aerosols taken from the interactive simulation, the QBO period changes from 24 to 12 - 17 months in simulations with sulfur dioxide injections 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.