Suppression of chlorine activation on aviation-produced volatile particles

[摘要] We examine the effect of nanometer-sized aircraft-induced aqueoussulfuric acid (H₂SO₄/H₂O) particles on atmospheric ozoneas a function of temperature. Our calculations are based on a previously derived parameterization for the regional-scale perturbations of the sulfatesurface area density due to air traffic in the North Atlantic Flight Corridor(NAFC) and a chemical box model. We confirm large scale model results that at temperaturesT>210 K additional ozone loss -- mainly caused by hydrolysis of BrONO₂ andN₂O₅ -- scales in proportion with the aviation-produced increase of the background aerosol surface area.However, at lower temperatures (< 210 K) we isolate two effects which efficiently reduce the aircraft-induced perturbation:(1) background particles growth due to H₂O and HNO₃ uptake enhance scavenging losses ofaviation-produced liquid particles and (2) the Kelvin effect efficiently limitschlorine activation on the small aircraft-induced droplets by reducing thesolubility of chemically reacting species. These two effects lead to a substantial reduction of heterogeneous chemistry on aircraft-induced volatileaerosols under cold conditions. In contrast we find contrail ice particlesto be potentially important for heterogeneous chlorine activation and reductions in ozone levels.These features have not been taken into consideration in previous global studies of the atmospheric impact ofaviation. Therefore, to parameterize them in global chemistry and transport models,we propose the following parameterisation: scale the hydrolysis reactions by the aircraft-induced surface areaincrease, and neglect heterogeneous chlorine reactions on liquid plume particlesbut not on ice contrails and aircraft induced ice clouds.

[学科分类] 大气科学