| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
Suspended particulate matter (SPM) is important due to the effect on global warming and air pollution. In a case of urban aerosol, we certified in Chiba the fraction of elemental carbon (EC) is 25% in fine particle (the particle diameter is less than 2 μm) and 9% in coarse particle (the size is larger than 2 μm) by sampling and analysis (Yabuki et al, CLEO 2003). The increase of EC amount brings larger absorption, i.e., larger extinction (scattering + absorption), which means larger lidar ratio S_1 (ratio of extinction to backscattering coefficient). Using the wavelength dependence of aerosol scattering property, we derived the vertical profiles of S_1 parameter and extinction coefficient of urban aerosol only from multi-wavelength lidar observation data. This is based on the lidar signal ratio of adjacent layers at different wavelengths should match the one predicted by Mie scattering theory (Yabuki et al, 2003). If we assume the aerosol model and MEE (mass to extinction efficiency: the inverse of extinction to mass concentration), then the concentration distribution at each altitude van be obtained. In real atmosphere, the aerosol condition changes due to. humidity. So humidity dependence of aerosol properties have been considered. The continuously observed lidar data ad the ground based aerosol concentration data were, compared. Then it is found that the mixture of aerosol in the boundary layer occurs in short period (within one hour) and the conversion coefficient at 532 nm is 0.08 to 0.1 (g/m^3)/(m^<-1>) [MEE : is 10 to 12.5 m^2/g]. This makes it possible to obtain the aerosol spatial profile in the urban boundary layer if the humidity is measured by another method: (Nofel et al, AE, 2004).
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