Role of zonally asymmetric ozone in modulating downward influence exerted by steady, transient and episodic wave forcing
In this study we focus on the role of ozone as a mediator of troposphere-stratosphere communication. Our emphasis is on downward propagation brought about by the effects of zonal asymmetries in ozone on planetary wave drag and eddy ozone convergences. We employ a mechanistic model of the extratropical atmosphere that couples radiative transfer, ozone transport, ozone photochemistry and the dynamical circulation. Three experimental scenarios are considered: steady wave forcing; transient wave forcing; and a localized momentum pulse that mimics the wave drag exerted by wave breaking. For each scenario we distinguish the relative importance of zonal-mean ozone and zonal asymmetries in ozone (ZAO) in affecting downward signal propagation. Preliminary results show that for certain steady wave forcing, ZAO can cause otherwise steady wind regimes to vacillate. For transient (periodic) wave forcing, ZAO produce vacillating wind regimes that differ markedly in amplitude and period from those that develop when zonal-mean ozone alone is considered. For a localized momentum pulse placed in the lower to mid stratosphere, ZAO weaken downward signal propagation and reduce its temporal persistence. These results are discussed in light of secular changes in stratospheric ozone and increasing greenhouse gas concentrations.