Atmos. Chem. Phys. Discuss., 8, 13159-13195, 2008
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Regional-scale modeling of near-ground ozone in the Central East China, source attributions and an assessment of outflow to East Asia – The role of regional-scale transport during MTX2006
J. Li1,2, Z. Wang2, H. Akimoto1, K. Yamaji1, M. Takigawa1, P. Pochanart1, Y. Liu1, and Y. Kanaya1
1Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
2State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry(LAPC), Nansen-Zhu International Research Center (NZC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, People's Republic of China

Abstract. A 3-D regional chemical transport model, the Nested Air Quality Prediction Model System (NAQPMS), with an on-line tracer tagging module was applied to study the source of the near-ground (<1.5 km above ground level) ozone at Mt. Tai (36.25°N, 117.10°E, 1534 m a.s.l.) in Central East China (CEC) during the Mount Tai eXperiment 2006 (MTX2006): regional ozone photochemistry and aerosol studies in Central East China in June, 2006. The model reproduced the temporal and spatial variations of near-ground ozone and other pollutants. In particular, the model captured highly polluted and clean cases well. The simulated near-ground ozone over CEC is 60–85 ppbv (parts per billion by volume), higher than those (20–50 ppbv) in Japan and over the North Pacific. The simulated tagged tracer indicates that the regional-scale transport of chemically produced ozone over other areas in CEC contributes to the most fractions (49%) of the near-ground mean ozone at Mt. Tai in June, rather than the in-situ photochemistry (12%). Due to high anthropogenic and biomass burning emissions, the contributions of the ground ozone from the southern part of CEC plays the most important role (32.4 ppbv, 37.9% of total ozone) in the monthly mean ozone concentration at Mt. Tai, which even reached 59 ppbv (62%) on 6–7 June 2006. The monthly mean horizontal distribution of chemically produced ozone from various source regions indicates that the spatial distribution of O3 over CEC is controlled by the photochemical reactions. In addition, the regional-scale transport of pollutants also plays an important role in the spatial and temporal distribution of ozone over CEC. The chemically produced ozone from the southern part of the study region can be transported northeastwardly to the northern rim of CEC. The mean contribution is 5–10 ppbv, and it can reach 25 ppbv during high ozone events. This work also studied the outflow of CEC ozone and its precursors, as well as their influences and contributions to the ozone level over adjacent regions/countries. It shows that the contribution of CEC ozone to mean ozone mixing ratios over Korea Peninsula and Japan is 5–15 ppbv, of which about half was due to the direct transport of ozone from CEC and half was contributed by the ozone produced locally by the transported ozone precursors from CEC.

Citation: Li, J., Wang, Z., Akimoto, H., Yamaji, K., Takigawa, M., Pochanart, P., Liu, Y., and Kanaya, Y.: Regional-scale modeling of near-ground ozone in the Central East China, source attributions and an assessment of outflow to East Asia – The role of regional-scale transport during MTX2006, Atmos. Chem. Phys. Discuss., 8, 13159-13195, doi:10.5194/acpd-8-13159-2008, 2008.
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