Ozone source attribution and its modulation by the Arctic oscillation during the spring months

Regionally, the AO can modulate ozone by up to 5 parts per billion by volume (ppbv). We examine the modulation of ozone produced from Asian, American, and European emissions separately, the modulation of ozone produced from all tropospheric emissions, and the modulation of ozone transported from the stratosphere.

During the positive phase of the AO, the simulations show a statistically significant decrease in zonally averaged ozone throughout the depth of the troposphere north of approximately 50°N. This decrease is attributed to a decrease in the stratospheric component of ozone. The longitudinal response of ozone to the AO in the upper troposphere is dictated by the changes in tropopause height associated with the AO, such that lower (higher) heights imply increased (decreased) ozone.