Local distribution of PM_(2.5) concentration over Osaka based on space and ground measurements

摘要

This work intends to estimate PM_(2.5) concentration over the mega city of Osaka in Japan based on both satellite and ground measurements. Our work is composed of the following steps. At first the relationship between PM_(2.5) 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 PM_(2.5) 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 PM_(2.5) are partially validated with the sampling data of PM_(2.5) at the surface.