Global QBO in Circulation and Ozone. Part II: A Simple Mechanistic Model

Open Access
Publisher Website
Google Scholar
Abstract
Although the phenomenon of equatorial quasi-biennial oscillation is relatively well understood, the problem of how the equatorially confined QBO wave forcing can induce a signal in the extratroics of comparable or larger magnitude remains unsolved. A simple mechanistic model is constructed to provide a quantitative test of the hypothesis that the phenomenon of extratropical QBO is mainly caused by an anomalous seasonal circulation induced by an anomalous Eliassen-Palm flux divergence. The anomaly in E–P flux divergence may be caused in turn by the relative poleward and downward shift of the region of irreversible mixing (breaking) of the extratropical planetary waves during the easterly phase of the equatorial QBO as compared to its westerly phase. The hemispheric nature of the anomaly wave forcing in solstice seasons (viz., no wave breaking in the summer hemisphere) induces a global circulation anomaly that projects predominantly into the first few zonal Hough modes of Plumb. Such a global QBO c... Abstract Although the phenomenon of equatorial quasi-biennial oscillation is relatively well understood, the problem of how the equatorially confined QBO wave forcing can induce a signal in the extratroics of comparable or larger magnitude remains unsolved. A simple mechanistic model is constructed to provide a quantitative test of the hypothesis that the phenomenon of extratropical QBO is mainly caused by an anomalous seasonal circulation induced by an anomalous Eliassen-Palm flux divergence. The anomaly in E–P flux divergence may be caused in turn by the relative poleward and downward shift of the region of irreversible mixing (breaking) of the extratropical planetary waves during the easterly phase of the equatorial QBO as compared to its westerly phase. The hemispheric nature of the anomaly wave forcing in solstice seasons (viz., no wave breaking in the summer hemisphere) induces a global circulation anomaly that projects predominantly into the first few zonal Hough modes of Plumb. Such a global QBO c...

This publication has 0 references indexed in Scilit: