Stratospheric photochemical ozone loss at mid-Latitudes: An overview

Models using climatological circulation and observed halogen and aerosol loadings fail to fully account for the magnitude of mid-latitude ozone depletion during the 1980s and early 1990s, the time period of rising halogen loading. Also, there has been a long-standing “ozone deficit problem” in the middle atmosphere. We shall examine the chemical mechanism for ozone loss in models by comparing calculated values of species that participate in key, rate limiting steps for ozone removal to observations. Our focus will be on model representation of ozone loss by the BrO+ClO, ClO+HO₂, and HO_x cycles. We will also assess the stratospheric bromine budget using satellite and balloon data, and discuss key factors that regulate the stratospheric injection of bromine derived from oceanic, biogenic precursors.