We observed vertical distributions of aerosols and clouds with a lidar on board R/V Mirai and analyzed latitudinal features using the data of four cruises in the western Pacific. According to the measured backscattering coefficient, aerosol density was generally high at latitudes above 25¿N where the westerly from the Asian continent prevailed. The wavelength dependence of the retrieved aerosol backscattering showed that the characteristics of aerosols in the continental air mass were clearly different from those at lower latitudes. Aerosol concentration in the boundary layer varied significantly in the lower latitudes and was correlated with surface wind speed. The wavelength dependence of aerosol backscattering indicated that aerosol particles were larger when surface wind speed was high. ¿ 2001 American Geophysical Union