Direct effects of aerosols on global warming/cooling

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In this research project, to assess the direct effect of aerosols on the global warming/cooling, physical/optical and chemical properties of aerosols were investigated based on ground-based and ship-board aerosol measurements around Japan. Results from long-term ground measurement at Chichi-jima and the R/V Shirase on-board measurement around Japan are summarized as follows :1) The aerosol single scattering albedo (SSA) is one of important optical parameters for aerosol characteristics. The SSA values observed at Chichi-jima were 0.98-1.0 under typical weather conditions with subtropical high pressure systems, 0.96-0.98 in spring (April) and around 0.9 in winter (January).2) From the R/V Shirase on-board aerosol measurement around Japan in early autumns of 2002-2005, typical three cases with different features of aerosol properties were found: (1) SSA=0.98-1.0 for a sea salt particle rich aerosol under clean maritime atmosphere, (2) SSA=0.94-0.98 for anthropogenic sulfate and soil dust rich aerosols under continental air mass, and (3) SSA=0.85-0.94 for pollution atmosphere contaminated by combustion products during transport over Japan from Chinese Continent.3) As shown above, we obtained a consistent result from both ground-based and ship-board measurements for optical and chemical properties of aerosols around Japan.