Evaluation of effect of suppresion due to increase of anthropogenic aerosols on the global warming

随着人类活动的增加，大气中人为气溶胶浓度的增加抑制了全球变暖。但这种抑制作用强烈地依赖于气溶胶在太阳波段的吸收率。因此，确定大气气溶胶吸收率的全球分布是很重要的。1995年5月至1996年10月在日本冲绳北方海多角观测了气溶胶总质量和化学成分的月平均浓度，并利用观测结果对气溶胶进行了化学表征，发现冲绳气溶胶由元素碳、有机物、硫酸盐、硝酸盐、铵、氯化物、海盐阳离子和土壤颗粒组成。冲绳气溶胶的总质量浓度为3-11 μ g/m^3，直径小于2 μ m。在春季，除了来自中国大陆的黄沙外，还输送了大量的人为硫酸盐、有机碳和元素碳颗粒。夏季大气颗粒物总质量浓度较低，但钒、镍和铜的含量占总质量的比例较高，表明冲绳气溶胶主要分布在西太平洋。夏季为0.95，冬季为0.90，年平均为0.92。这表明冲绳附近西太平洋海洋气溶胶的吸收能力很小，对全球变暖的抑制能力也很小。

An increase of atmospheric concentrations of anthropogenic aerosols with human activities suppresses the global warming. The suppresion, however, depends strongly on absorptivity of the aerosols in solar wavelengths region. It is, thus, important to determine the global distribution of the absorptivity of atmospheric aerosols. In the study, we measured monthly mean atmospheric concentration of total mass and chemical components of the aerosols from May 1995 through October 1996 at Cape Hedo, northern edge of Okinawa island, Japan, and chemically characterized the aerosols by using the measurement results.We found that Okinawa aerosol consisted of elemental carbon, organics, sulfate, nitrate, ammonium, chloride, sea-salt cations and soil particles. Total mass concentration of the Okinawa aerosol was 3-11 mug/m^3 less than 2mum in diameter. In spring a large amount of anthropogenic sulfate, organic and elemental carbon particles were transported in addition to Yellow sands from Continental China. In summer, on the other hand, the atmospheric concentration of the total particulate mass was low, but the ratio of vanadium, nickel and cupper contents to the total mass were high, which indicated that the anthropogenic aerosols were distributed over the western Pacific Ocean.Based on the chemical characterization, we calculated a single scattering albedo of the Okinawa aerosol. It was 0.95 in summer, 0.90 in winter and 0.92 in annual average. It means that the western Pacific maritime aerosol around Okinawa has little absorptivity and capability of suppressing the global warming due to the increase.