Open AccessImpacts of Asian megacity emissions on regional air quality during spring 2001
Author(s) -
Guttikunda Sarath K.,
Tang Youhua,
Carmichael Gregory R.,
Kurata Gakuji,
Pan Li,
Streets David G.,
Woo JungHun,
Thongboonchoo Narisara,
Fried Alan
Publication year - 2005
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jd004921
Subject(s) - megacity , air quality index , environmental science , context (archaeology) , bay , air pollution , beijing , emission inventory , chemical transport model , meteorology , climatology , aerosol , atmospheric sciences , geography , geology , oceanography , economy , chemistry , archaeology , organic chemistry , china , economics
Measurements from the Transport and Chemical Evolution over the Pacific (TRACE‐P) and Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) field experiments obtained during the period of March–April 2001 are used to evaluate the impact of megacity emissions on regional air quality in east Asia. A classification method built upon back trajectory analysis and sensitivity runs using the Sulfur Transport and Emissions Model 2001 (STEM‐2K1) regional chemical transport model are used to identify the aircraft observations that were influenced by megacity emissions. More than 30% of measurement points are classified as urban points, with a significant number of plumes found to have originated from Shanghai, Qingdao, Beijing, Taiyuan, Tianjin and Guiyang, Seoul, and Pusan. These data are then analyzed, and chemical characteristics of these megacities are compared. Emission estimates for the megacities are also presented and discussed in the context of expected similarities and differences in the chemical signals in the ambient air impacted by these cities. Comparisons of the observation‐based ratios with emission‐based estimates are presented and provide a means to test for the consistency of the emission estimates. The observation‐based ratios are shown to be generally consistent with the emissions ratios. The megacity emissions are used in the STEM‐2K1 model to study the effects of these emissions on criteria and photochemical species in the region. Over large portions of the Japan Sea, Yellow Sea, western Pacific Ocean, and the Bay of Bengal, megacity emissions contribute in excess of 10% of the near‐surface ambient levels of O 3 , CO, SO 2 , H 2 SO 4 , HCHO, and NO z . The megacity emissions are also used to study ozone levels in Asia under a scenario where all cities evolve their emissions in a manner such that they end up with the same VOC/NO x emission ratio as that for Tokyo. Monthly mean ozone levels are found to increase by at least 5%.