OPTICAL PROPERITES OF ATMOSPHERIC AEROSOLS IN THE PACIFIC OCEAN

Abstract

Aerosols optical models are necessary to retrieve aerosol distributions from satellite data and to estimate aerosol direct climate forcing, however, aerosol optical properties such as single scattering albedo (ω) and optical thickness are rare information over ocean. In this study, the aerosol optical and chemical properties were measured from 1999 to 2003 in the western Pacific Ocean on board the research vessel Mirai. We encountered mainly four air masses which included maritime air mass, air mass influenced by fossil fuel combustion, that influenced by biomass burning, and dust plume in these cruises. The values of ω ranged from 0.68 in biomass burning to 0.99 in marine air mass. The region between 30° N and 40° N, air mass was influenced by aerosols emitted from fossil fuel combustion both in the summer and winter cruises. Since absorptive aerosols were measured in the winter cruise, the mean value of ω in this region in the winter cruise was 0.74, while transparent aerosols were measured in the summer cruise (mean value of ω was 0.92). This seasonal difference mainly comes from a difference in the concentration of elemental carbon.