Effects of interannual variability of meteorological inputs on aircraft perturbations represented in the CAM5-Chem

Abstract:

Three-dimensional chemical-transport model (CTM) studies of human effects on the atmosphere, including those of aircraft, have typically employed a single representative year of atmospheric meteorology to drive the model (i.e simulations have been run in a specified dynamics mode). The current and likely near-future aircraft fleets operate mostly near the tropopause, a region sensitive to changes in dynamics that are likely among different years. This study explores the variation in aviation induced ozone perturbations using the Community Atmosphere Model with Chemistry, version 5 (CAM5) over eleven years of meteorological fields which represent eleven years of interannual variability. Meteorology to drive the model was supplied by eleven years of MERRA (Modern Era Retrospective-Analysis for Research and Applications) reanalysis for years 2000-2011. The aviation emissions used were obtained from the Aviation Environmental Design Tool (AEDT) for the year 2006.

Results indicate a very little year to year variation (less than 10%) in the derived changes in aviation-induced ozone. This result led to the conclusion that aircraft effects modeling under a single meteorology year should suffice within current model uncertainties. It can be further concluded that aviation induced signals obtained in coupled simulations could not be entirely masked by the model interannual variability.