Long‐range transport of the April 2001 dust clouds over the subtropical East Asia and the North Pacific and its impacts on ground‐level air pollution: A Lagrangian simulation

Abstract

One of the most remarkable Asian dust storms occurred in April 2001, during the periods of the Aerosol Characterization Experiment (ACE)‐Asia and the Transport and Chemical Evolution Over the Pacific (TRACE‐P) field experiments. Our high‐resolution Lagrangian simulations and the detailed comparisons with the Total Ozone Mapping Spectrometer (TOMS)‐Aerosol Index (AI) data, the Geostationary Meteorological Satellite (GMS)‐5 derived dust distribution, and the ground‐level ambient air particulate matter measurements over Taiwan in the subtropical East Asia reveal several features which were not reported before. We found that (1) the trans‐Pacific long‐range transport was dominated by the dust emissions from the natural source over the Gobi desert and the anthropogenic source over east China before 6–7 April, while the southward long‐range transport to the subtropical East Asia were mainly contributed by the dust emissions from natural source over the Taklamakan and the Gobi, and the anthropogenic source over east China after 6–7 April; (2) the southward long‐range transport implies that the anthropogenic pollution is ahead of the cold front (where the precipitation washes out the particulate matter), while the dust is behind the cold front. (3) The dust emissions from the Gobi during 7–9 April, anthropogenic emissions from east China during 9–10 April, and dust emissions from the Taklamakan during 1–4 April appear to have the most significant impacts on the ground‐level particulate matter concentrations over Taiwan. The simulated particle emitted from desert regions before 6–7 April mainly confined to the Gobi and the Taklamakan regions until 6 April when they became highly mobile for the long‐range transport by the large‐scale cyclonic activity and its associated cold air outbreak. The southward transport characteristics simulated here are consistent with the aerosol characterization observed at Taiwan during this period. Our simulations reveal that the rapid trans‐Pacific transport processes occurred on 12 April contribute to the extensive areas of elevated AI values prevail over the North Pacific during this day.