A43G-0381
Baseline Carbon Monoxide and Ozone in the Northeast U.S. Over 2001 – 2010
Thursday, 17 December 2015
Poster Hall (Moscone South)
Ying Zhou, SUNY College of Environmental Science and Forestry, Syracuse, NY, United States, Huiting Mao, SUNY-ESF--Dept of Chemistry, Syracuse, NY, United States, Kenneth L Demerjian, University at Albany - SUNY, Albany, NY, United States, Christian Hogrefe, U.S. Environmental Protection Agency, Durham, NC, United States and Jane Liu, University of Toronto, Toronto, ON, Canada
Abstract:
Baseline CO and O3 were studied at seven rural sites in the Northeast U.S. during varying periods over 2001 – 2010. Baseline CO decreased significantly at rates ranging from -4.3 to -2.3 ppbv yr-1 at most sites, except at Castle Spring (CS). Baseline O3 did not display a significant long term trend at any of the sites, resulting probably from relatively constant mixing ratios of CH4 in the 2000s and opposite trends in NOx emissions worldwide. On a seasonal basis, there were no trends in springtime and wintertime baseline CO at Mt. Washington (MWO) (1917 km asl) and Whiteface Mountain (WFM) (1484 km asl), the highest sites, probably due to decreasing CO emissions in the U.S. and increasing emissions in Asia. Springtime and wintertime baseline O3 at Thompson Farm (TF) increased significantly at a rate of 2.4 and 2.7 ppbv yr-1, respectively, most likely linked to nitrogen oxides (NOx) emissions reductions over urban and industrial areas. During the positive North Atlantic oscillation (NAO) years, lower springtime baseline O3 was found in the study region, which was linked to less solar flux, weakened stratospheric intrusion, and intensified continental export. The lowest baseline CO at Appledore Island (AI), Pack Monadnock (PM), TF, Pinnacle State Park (PSP), WFM and the lowest baseline O3 at AI, PM, and PSP in summer 2009 were linked to the negative phase of the Arctic oscillation (AO), when more frequent cyclone activity brought more clean air masses from the Arctic region to midlatitudes. It was also found that ~38% of summertime baseline CO variability in the study region, could be explained by CO emissions from forest fires in Russia and ~22% by emissions from forest fires in Canada. The findings of this study suggested impacts of increasing Asian emissions, NOx emissions from the urban corridor, biomass burning emissions, and meteorological conditions (e.g. cyclone activity, AO, and NAO) should be considered when evaluating the air quality in the Northeast U.S.
