Superposition of Gobi Dust and Southeast Asian Biomass Burning: The Effect of Multisource Long-Range Transport on Aerosol Optical Properties and Regional Meteorology Modification

One unique long-range transport event with multiple layers of aerosol plumes was observed over Taiwan during 29–31 March 2006. A synergy of ground-based observation, remote sensing, and backward trajectory simulation collectively indicated the high-altitude (above 3 km) plume originated from biomass burning in Southeast Asia while the midaltitude (around 0.8–2 km) plume was attributed to dust from the Gobi Desert. Aerosol optical properties measured at a low-altitude site were characterized of abundant coarse mode particles and increased single scattering albedo as a function of increased wavelength, indicating the influence from dust particles. While at a high mountain site (elevation of ~3 km), aerosol optical depth was elevated by a factor of 3–4 compared to its background value and mainly comprised of fine particles. It was diagnosed that the high-altitude aerosols were influenced by the transported smoke plumes but exempted from dust. Simulation of the meteorological conditions against a Taiwan-wide meteorology network showed strong near surface temperature rise of more than 2° during this long-range transport event as well as for the vertical temperature profiles. Both dust and biomass burning aerosol plumes via long-range transport contributed significantly to the atmospheric warming, resulting in strong instantaneous aerosol radiative forcing of 46.0 W/m² in the atmosphere. A “double dome” warming effect mechanism was proposed that both biomass burning and dust plumes above the boundary layer could efficiently reserve the solar energy and heat the lower troposphere.