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Keywords:

  • East Asian dust;
  • pollution;
  • optical properties;
  • transpacific;
  • satellite;
  • aerosol mixing

Abstract

We investigate changes in the optical properties of a large dust plume originating from East Asian deserts during its transport over the northwestern Pacific Ocean in March 2013. The study makes use of observational products from two sensors in the NASA A-Train satellite constellation, the Moderate Resolution Imaging Spectroradiometer and the Cloud-Aerosol Lidar with Orthogonal Polarization. Forward trajectory clustering analysis and satellite observations show that dust initiating from the Taklimakan and Gobi deserts experienced thorough mixing with industrial pollution aerosols shortly after leaving the source region and were lofted by a strong midlatitude weather system to more than 4 km in height. The dust plume accompanied the weather system and reached the east coast of the North American continent within 7–10 days. The dust aerosols became spectrally absorptive during transport due to mixing with other aerosol types such as soot. Furthermore, a decrease in the depolarization ratio suggests that the complexities in aerosol particle morphologies were reduced during transport over the ocean. More than half of the dust aerosol layers surviving the trans-Pacific transport were polluted and exhibited different optical properties and radiative effects from those of pure dust.