Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 6 5 2006 10.5194/acpd-6-10183-2006 http://www.atmos-chem-phys-discuss.net/6/10183/2006/ http://www.atmos-chem-phys-discuss.net/6/10183/2006/acpd-6-10183-2006.html http://www.atmos-chem-phys-discuss.net/6/10183/2006/acpd-6-10183-2006.pdf 10183 10216 2006-10-12 Long-range transport of Asian dust and air pollutants to Taiwan: observed evidence and model simulation C.-Y. Lin Z. Wang W.-N. Chen S.-Y. Chang C. C. K. Chou N. Sugimoto X. Zhao Research Center for Environmental Changes, Academia Sinica, Taipei 115, Taiwan Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China National Institute for Environmental Studies, Onogawa, Tsukuba, Japan Long-range transport of Asian dust and air pollutants are major environmental concerns of Taiwan during the winter monsoon season when northeasterly winds prevail following passages of cold fronts. Based on hourly measurements of Taiwan Environmental Protection Administration (TEPA) air quality monitoring stations, Lidar and in-situ IC, a significant long-range transport dust and air pollutants event on 18 March 2005 has been identified. During this episode, drastically elevated concentrations of PM₁₀, CO and SO₂ along with the strong northeasterly on 18 March were observed over background Wanli station, with peaks of about 170 μgm^−3, 1.0 PPM and 14 ppb, respectively. We have found that air masses of air pollutants and Asian dust are transported separately. The major component of the first PM₁₀ peak were air pollutants, evidenced by the consistent peaks of SO₄^2− and NO₃^− measured by in-situ IC, while no significant depolarization was measured by Lidar. In contrast, the evident non-spherical particles and hourly PM₁₀ concentration consistently varied with Ca²⁺ indicating that mineral dust was the major component of the second peak. Numerical results showed significant agreement of temporal and vertical variation of aerosol concentration with observations. The phenomena of split air parcels between air pollutants and Asian dust transported to Taiwan are strongly associated with the transport paths and stable and dry atmospheric boundary conditions.