Department of Earth System Science

We study the mechanisms driving stratosphere-troposphere exchange of ozone fluxes within a chemistry-transport model. For years 2004–2006, year-round, most of the stratosphere-to-troposphere flux of O₃ is associated with shear and folding around the subtropical jet, and this jet-related flux peaks for the northern hemisphere in May. Over the northern mid-latitude continents, however, surface convection penetrates to stratospheric levels of O₃ (250 ppb), enhancing the O₃ flux by 19% of the northern hemisphere total, and shifting the peak flux to June. This convection-related O₃ flux represents 49% of the total over northern mid-latitudes in June.