Changes in the photochemical environment of the temperate North Pacific troposphere in response to increased Asian emissions

摘要: [1] Measurements during the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) field study characterized springtime, eastern Pacific ozone distribution at two ground sites, from National Oceanic Atmospheric Administration WP-3D aircraft, a light aircraft operated by University of Washington. D. Jaffe colleagues compared with measurements made in region over previous decades show that average levels midlatitude have systematically increased ∼10 ppbv last decades. Here we provide substantial evidence marked change photochemical environment springtime troposphere North is responsible for this O3. This evidenced ITCT 2K2 (1) larger increases minimum observed to more modest maximum levels, (2) peroxyacetyl nitrate (PAN) parallel trends NOx emissions, (3) decreased efficiency O3 destruction, i.e., less negative tendency (or net rate production; P(O3)). changed hypothesized be due anthropogenic emissions Asia, which are believed substantially preceding study. We propose their influence has tropospheric photochemistry predominately destroying nearly producing. However, chemical transport model calculations indicate possible confounding factor; unusual tropical air western one early may played role apparent photochemistry.