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

人类活动引起的大气中人为气溶胶浓度的增加抑制了全球变暖。然而，这种抑制在很大程度上取决于气溶胶在太阳波长区域的吸收率。因此，确定大气气溶胶吸收率的全球分布是很重要的。在研究中，我们测量了1995年5月至1996年10月在日本冲绳岛北部边缘的合道角的气溶胶的总质量和化学成分的月平均大气浓度，并利用测量结果对气溶胶进行了化学表征。我们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 ~ 11mug /m^3，直径小于2mum。春季，除了中国大陆的黄沙外，还携带了大量人为的硫酸盐、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、镍和铜含量占总质量的比例较高，表明人为气溶胶主要分布在西太平洋上空。基于化学特性，我们计算了冲绳气溶胶的单次散射反照率。夏季为0.95，冬季为0.90，年平均值为0.92。这意味着冲绳周围的西太平洋海洋气溶胶由于增加，吸收能力和抑制全球变暖的能力都很小。

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.