Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere

Abstract. The impact of very short-lived (VSL) halogenated source species on the ozone layer and surface erythemal ultraviolet radiation (UV_ERY) is investigated in the context of geo-engineering of climate by stratospheric sulfur injection. For a projected 2040 model atmosphere, consideration of VSL halogens at their upper limit results in lower ozone columns and higher UV_ERY due to geo-engineering for nearly all seasons and latitudes, with UV_ERY rising by 12% and 6% in southern and northern high latitudes, respectively. When VSL halogen sources are neglected, future UV_ERY increases due to declines in ozone column are nearly balanced by reductions of UV_ERY due to scattering by the higher stratospheric aerosol burden in mid-latitudes. Consideration of VSL sources at their upper limit tips the balance, resulting in annual average increases in UV_ERY of up to 5% in mid and high latitudes. Therefore, VSL halogens should be considered in models that assess the impact of stratospheric sulfur injections on the ozone layer.