Atmospheric Chemistry Signatures of an Equatorially Symmetric Matsuno–Gill Circulation Pattern

Abstract Matsuno–Gill circulations have been widely studied in tropical meteorology, but their impact on stratospheric chemistry has seldom explicitly evaluated. This study demonstrates that, a model nudged to reanalysis, anticyclonic Rossby wave gyres that form near the tropopause as result of equatorially symmetric heating troposphere provide dynamical mechanism influence and subtropical atmospheric during near-equinox months. The flow entrains extratropical air from higher latitudes into deep tropics both hemispheres induces cooling already cold upper-troposphere/lower-stratosphere (UTLS) region. Both these aspects circulation allow heterogeneous chlorine activation sulfuric acid aerosols proceed rapidly, primarily via HCl + ClONO 2 reaction. Precipitation rates reanalysis are shown be consistent with response patterns months interest. analyzes specified dynamics simulations Whole Atmosphere Community Climate Model (SD-WACCM) without demonstrate substantially distributions of, for example, NO ClO UTLS subtropics hemispheres. provides previously unrecognized spatial structures composition changes