Local distribution of PM2.5 concentration over Osaka based on space and ground measurements

This work intends to estimate PM2.5 concentration over mega city Osaka in Japan based on both satellite and ground measurements. Our work is composed of the following steps. At first the relationship between PM2.5 and aerosol optical thickness (AOT) is derived by using the ground measurements with sun photometer and PM-sampler, respectively. In addition vertical distribution of aerosol particles are also investigated by LIDAR measurements. The second step is to retrieve columnar AOT distribution from the space-based reflectance information with CAI (cloud aerosol imager) on GOSAT (greenhouse gases observing satellite). Note that, the PM2.5 measurements indicate the surface level concentration of the atmospheric particles, and hence the columnar AOT distribution should be converted to the surface level aerosol optical depth (AOD) based on the aerosol extinction profile with LIDAR. Finally, PM2.5 distribution is obtained from the relationship derived at the first step. The obtained results of PM2.5 are partially validated with the sampling data of PM2.5 at the surface.