A 5-YEAR SIMULATION OF SUPERSONIC AIRCRAFT EMISSION TRANSPORT USING A3-DIMENSIONAL MODEL

A 5-year simulation of supersonic aircraft exhaust using a three-dimen sional transport model has been completed using winds from the NASA/Go ddard data assimilation system. A tracer based on emission rates of re active nitrogen species (NOy) for all forecasted night routes is conti nuously injected into the model. A parameterized upper stratospheric l oss mechanism and a tropospheric sink due to rainout approximately bal ance the nitrogen emissions after several years of integration. Maximu m values for exhaust NOy occur during the northern hemisphere (NH) sum mer months, and minimum values occur during winter. The pollutant is m ost zonally asymmetric during the NH summer. The peak values are never more than twice the zonal mean. This supports the use of zonally aver aged two-dimensional models to evaluate the impact of the exhaust on t he lower stratospheric composition. Budget calculations from the trans port model show that most exhaust released in the NH is transported do wnward into the troposphere, where it is destroyed. In the model, abou t 15-20% of exhaust released poleward of 30 degrees N is transported i nto the tropics, where it is lofted. The stratospheric residence time for the exhaust is estimated to be 13 months.