Decadal Ozone Trends in the Eastern Pacific

Measurements during ITCT 2K2 characterized the springtime, eastern Pacific ozone distribution at two ground sites, from the NOAA WP-3D aircraft, and from a light aircraft. Asian anthropogenic emissions are believed to have increased substantially over the 2 decades preceding the study. Here we will compare the 2002 ozone distribution with measurements made in the region over the 2 previous decades. This comparison provides substantial evidence that the photochemistry in the springtime troposphere of the Pacific has changed in response to the increasing anthropogenic emissions. Preliminary analysis of the available data suggests that ozone levels of the Eastern Pacific have systematically increased by about 0.5 ppbv/yr., i.e. about 10 ppbv in the last two decades.