http://adsabs.harvard.edu/abs/2015EGUGA..17.1863T
Heterogeneous reactions of TiO2 aerosol particles with N2O5 and ClONO2 and their implications for stratospheric particle injection Authors: Tang, Mingjin; Keeble, James; Telford, Paul; Pope, Francis; Rkiouak, Laylla; Abraham, Luke; Braesicke, Peter; Pyle, John; Mcgregor, James; Watson, Matt; Cox, Tony; Kalberer, Markus EGU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. id.1863 04/2015 Abstract Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space has been suggested as a solar radiation management scheme for climate engineering. Several minerals, including TiO2, have been as possible candidate particles (instead of sulfuric acid) to be injected into the stratosphere, due to their high refractive indices. However, their heterogeneous reactivity towards important reactive trace gases in the stratosphere has seldom been investigated, impeding us from a reliable assessment of their impact on stratospheric O3. In this work, the heterogeneous reactions of airborne TiO2 particles with N2O5 and ClONO2 have been studied at room temperature and at different RH, using an atmospheric pressure aerosol flow tube. The uptake coefficient of N2O5, γ(N2O5), increased from ~1.8E-3 at 5% RH to 4.5E-3 at ~60% RH for TiO2, significantly smaller than that for sulfuric acid particles in the stratosphere. The uptake of ClONO2 onto TiO2 aerosols particles have been found to be quite inefficient, with γ(ClONO2) not larger than 1E-3. Therefore, compared to stratospheric sulfuric acid particles, TiO2 particles show similar reactivity towards ClONO2 and much less reactivity towards N2O5. The UKCA chemistry-climate model has been used to assess the impact of TiO2 particles on stratospheric chemistry. A few scenarios have been constructed for TiO2 particle injection to have the same radiative effect as the eruption of Mt. Pinatubo. We find that the impact of TiO2 injection on stratospheric N2O5 is much smaller than the eruption of Mt. Pinatubo. The heterogeneous reaction of ClONO2 with TiO2 particles is being included in the model, and a comprehensive assessment of the effect of TiO2 injection on stratospheric chemistry will be presented. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
