Abstract
To investigate the diurnal variation of SPM (Suspended Particulate Matter) emitted from automobiles in metropolitan area, meso-scale numerical simulations were carried out using RAMS (Atmospheric Modeling System). The following results were obtained;
(1) The wind field dominately affect the diurnal variation of SPM. When simulated wind fields agree with those of the observation, diurnal variations of SPM also agree well with those of the observation.
(2) Sea breeze and boundary layer have strong influence on the SPM variation. In the morning, SPM is relatively high concentration, since a stable layer restrains vertical diffusion of SPM. In the afternoon, SPM concentrations suddenly decrease in accordance with the sea breeze and boundary layer development. Atmosphere in the BL is well mixed and SPM is diffused and advected.
