Evaluating ozone depletion from very short-lived halocarbons

A new approach is needed for calculating the ozone depletion potential (ODP ) of short-lived gases with mean lifetimes less than 100 days. Clearly, the ozone loss from such gases depends strongly on the location and season of emissions. It is proposed that delivery to the tropical tropopause is a sur rogate for the amount of halogen entering the stratosphere. Thus 3-D global models, with accurate simulation of tropospheric chemistry and transport, can calculate the ODP specific to tropical sources (high) and high-latitude sources (low). The ODP of CH2BrCH2CH3 from this analysis ranges from 0.000 2 to 0.06 depending on the location and season of emissions.