Sensitivity of Arctic ozone loss to polar stratospheric cloud volume and chlorine and bromine loading in a chemistry and transport model

Abstract

The sensitivity of Arctic ozone loss to polar stratospheric cloud volume (VPSC) and chlorine and bromine loading is explored using chemistry and transport models (CTMs). One simulation uses multi‐decadal winds and temperatures from a general circulation model (GCM). Winter polar ozone loss depends on both equivalent effective stratospheric chlorine (EESC) and polar vortex characteristics (temperatures, descent, isolation, polar stratospheric cloud amount). The simulation reproduces a linear relationship between ozone loss and VPSC in agreement with that derived from observations for 1992–2003. The relationship holds for EESC within ∼85% of its maximum (∼1990–2020). For lower EESC the ozone loss varies linearly with EESC unless VPSC ∼ 0. A second simulation recycles a single year's winds and temperatures from the GCM so that polar ozone loss depends only on changes in EESC. This simulation shows that ozone loss varies linearly with EESC for the entire EESC range for constant, high VPSC.