气候变化领域集成服务门户

Interannual variability in baseline carbon monoxide (CO) and ozone (O-3), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001-2010. Annual baseline CO exhibited statistically significant decreasing trends (-4.3 to -2.3 ppbv yr(-1)), while baseline O-3 did not display trends at any site. In examining the data by season, wintertime and springtime baseline CO at the two highest sites (1.5 km and 2 km asl) did not experience significant trends. Decadal increasing trends (similar to 2.55 ppbv yr(-1)) were found in springtime and wintertime baseline O-3 in southern New Hampshire, which was associated with anthropogenic NOx emission reductions from the urban corridor. Biomass burning emissions impacted summertime baseline CO with similar to 38% variability from wildfire emissions in Russia and similar to 22% from Canada at five sites and impacted baseline O3 at the two high elevation sites only with similar to 27% variability from wildfires in both Russia and Canada. The Arctic Oscillation was negatively correlated with summertime baseline O-3, while the North Atlantic Oscillation was positively correlated with springtime baseline O-3. This study suggested that anthropogenic and biomass burning emissions, and meteorological conditions were important factors working together to determine baseline O-3 and CO in the Northeast U.S. during the 2000s. (C) 2017 Elsevier Ltd. All rights reserved.