Uncertainty in Deriving Atmospheric Perturbations due to Aviation, Shipping, and Road Transport

A preponderance of evidence from atmospheric measurements, laboratory work and chemistry-transport modeling (CTM) demonstrates that emissions from the transport sector are altering the composition of the global atmosphere in ways detrimental to climate and air quality. CTMs are the essential tools for quantifying these changes over seasons and scenarios. We look at some results from the EU QUANTIFY project -- which UCI participated in -- whose objective is to quantify the climate impact of transportation emissions for both present and future. We have results from CTMs using the same emission inventories and meteorological fields. We examine the range of model results for the impact of the transport sector on tropospheric ozone as a possible measure of uncertainty. In addition we perform a series of sensitivity studies with the UCI CTM. We select key uncertainties in our own model (e.g., lightning NOx, scavenging, convection) to understand if these can explain the differences across the QUANTIFY models, and whether the variance across this ensemble of models may represent some of the uncertainty in this assessment.