Direct comparison of extinction coefficients derived from Mie-scattering lidar and number concentrations of particles, subjective weather report in Japan

- Two components of extinction coefficient (dust and sphere) below 500 m are continuously retrieved by several lidars in Japan.
- Number concentration of particles measured at the surface by OPC corresponded with dust/sphere extinction coefficients.
- Kosa (Asian dust) reported at meteorological observatories sometimes do not suite with dust extinction coefficient by lidar.
- Report of En׳mu (haze) and period of higher spherical extinction coefficient were well corresponded.

Two components of the lidar extinction coefficient, the dust extinction and the spherical particles extinction, were obtained from observations made by the National Institute for Environmental Studies lidar network in Japan. These two extinctions were compared with the number concentration of particles measured by an optical particle counter, and with subjective weather reports recorded at the nearest meteorological observatories. The dust extinction corresponded well with the number concentration of large particles with diameters as great as 5μm and during dry conditions with the number concentration of particles larger than 2μm. The relationship between the spherical particle extinction and the number of small particles was nearly constant under all conditions. Asian dust was sometimes reported by meteorological observatories in the period of lower dust extinction. This indicates contradicting relationship between human-eye based reports and optical characteristics observed by lidars in some cases. The most consistent results between lidar observation and meteorological reports were obtained in dry mist conditions, in which lidars exhibited higher spherical extinction as expected by the definition of the atmospheric phenomenon of dry mist or haze.