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Uchiyama, A., A.Yamazaki, R. Kudo, E. Kobayashi, H. Togawa, and D. Uesawa, 2014: Continuous ground-based observation of aerosol optical properties at Tsukuba, Japan: Trend and climatology. J. Meteor. Soc. Japan, 92A, 93-108.
https://doi.org/10.2151/jmsj.2014-A06

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Highlights:

• To investigate aerosol optical properties, the Meteorological Research Institute has been continuously measuring scattering and absorption coefficients since January 2002 in dry air conditions at Tsukuba, Japan.
• We used these optical data to investigate trends of aerosol properties and climatology.
• The results showed that most aerosol characteristics had seasonal variation and decreasing or increasing trends significant at the 95 % confidence level.
• From 2002 to 2013, the extinction coefficient at 550 nm and absorption coefficient at 530 nm had statistically significant decreases of –1.5 × 10^–6 and –5.4 × 10^–7 m^–1 year^–1, respectively. The single scattering albedo (SSA) at 550 nm had a significant increasing trend of 7.4 × 10^–3 year^–1.
• The increasing trend of 2.1 × 10^–2 year^–1 in the absorption Ångström exponent from 2006 to 2013 was significant. This tendency suggests a compositional change of light-absorbing aerosol.
• The analysis using the extinction Ångström exponent showed that aerosol characteristics were dependent on the extinction Ångström exponent.
• The aerosol characteristics estimated from optical data were consistent with those derived from radiometer data.