Plume transformation index (PTI) of the subsonic aircraft exhausts and their dependence on the external conditions

Abstract

A concept of the PTI is proposed to characterize the photochemical interactions of aircraft exhausts with the ambient air. The PTI is the ratio of NO x , CO, , ozone, and NO y transformed in the plume during its lifetime period t p to NO x and CO released into the plume initially. An estimate of t p is calculated by prescribing the 10% excess of emitted ( NO x ) p in the plume over the ( NO x ) a of the ambient air at the end of plume life. Simple analytical formulas for PTI are obtained from the known plume box model. The t p , PTI of NO x , HNO 3 and O 3 are calculated and analyzed for different moments of releases during the daytime in and out of flight corridor. The in‐plume NO x conversion to HNO 3 and O 3 enhancement are found to be the largest in daytime, in July and in the lower stratosphere.