Optical properties of aerosols during APEX and ACE-Asia experiments

Sun/sky photometry and polarimetry of atmospheric light have been undertaken by multispectral photometers (CE‐318‐1 and ‐2, Cimel Electronique, France) and a polarimeter (PSR‐1000, Opto Research, Japan) over Amami, Noto, and Shirahama, Japan, during APEX‐E1, ‐E2, and ACE‐Asia field campaigns. Radiometers provide us with the optical thickness of aerosols and Ångström exponent. Other aerosol characteristics, e.g., size distribution, refractive index, etc., are retrieved based on each inversion method corresponding each equipment. The former takes a standard AERONET processing, and the latter is according to our own procedure to analyze the polarimetry with PSR‐1000. After several aerosol parameters are derived, the HYSPLIT4 backward trajectory analysis is adopted to search the origin of aerosols. It is shown from these ground measurements that aerosol optical thickness, Ångström exponent, and refractive index are classified into two typical categories as a background type detected in winter, and a soil dust type appeared in Asian dust events in spring. Further, it is found that the obtained size distribution of Asian dust indicates the dominance of large particles.