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

A concept of the PTI is proposed to characterize the photochemical interact ions of aircraft exhausts with the ambient air. The PTI is the ratio of NOx , CO, ozone, and NOy transformed in the plume during its lifetime period t( p) to NOx and CO released into the plume initially. An estimate of t(p) is calculated by prescribing the 10% excess of emitted (NOx)(p) in the plume o ver the (NOx)(a) of the ambient air at the end of plume life. Simple analyt ical formulas for PTI are obtained from the known plume box model. The t(p) , PTI of NOx, HNO3 and O-3 are calculated and analyzed for different moment s of releases during the daytime in and out of flight corridor. The in-plum e NOx conversion to HNO3 and O-3 enhancement are found to be the largest in daytime, in July and in the lower stratosphere.