The impact of global aviation NO_x emissions on tropospheric composition changes from 2005 to 2011

The impact of aviation NO_x emissions from 2005 to 2011 on the chemical composition of the atmosphere has been investigated on the basis of integrations of the 3-D global chemical and transport model, STOCHEM-CRI with the novel CRIv2-R5 chemistry scheme. A base case simulation without aircraft NO_x emissions and integrations with NO_x emissions from aircraft are inter-compared. The sensitivity of the global atmosphere to varying the quantity and the geographical distribution of the global annual aviation NO_x emissions is assessed by performing, for the first time, a series of integrations based on changing the total mass and distribution of aircraft NO_x emissions derived from air traffic movements recorded between 2005 and 2011. The emissions of NO_x from the global fleet based on actual records of air traffic movements between 2005 and 2011 increased the global tropospheric annual mean burden of O₃ by 1.0 Tg and decreased the global tropospheric annual mean burden of CH₄ by 2.5 Tg. The net NO_y and O₃ production increases by 0.5% and 1%, respectively between 2005 and 2011 in total. At cruise altitude, the absolute increase in the modelled O₃ mixing ratios is found to be up to 0.7 ppb between 2005 and 2011 at 25°N–50°N.