NAME = Kentaroh Suzuki ORGANIZATION = Center for Climate System Research, University of Tokyo ADDRESS = 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 COUNTRY = JAPAN PHONE = +81-3-5453-3950 FAX = +81-3-5453-3964 E-MAIL = kenta@ccsr.u-tokyo.ac.jp POSTER_ONLY = no THEME = T2 DATE = 30-Jul-04-12:32:43 ABSID = T2KS30Jul04123243 TITLE = Numerical study of the aerosol effect on water cloud optical properties with nonhydrostatic spectral microphysics cloud model AUTHOR_1 = Kentaroh Suzuki INSTITUTION_1 = Center for Climate System Research, University of Tokyo PRESENTER = AUTHOR_1 AUTHOR_2 = Teruyuki Nakajima INSTITUTION_2 = Center for Climate System Research, University of Tokyo AUTHOR_3 = Takamichi Iguchi INSTITUTION_3 = Center for Climate System Research, University of Tokyo AUTHOR_4 = Gorou Asanuma INSTITUTION_4 = NTT west Japan AUTHOR_5 = Takashi Y. Nakajima INSTITUTION_5 = Earth Observation Research Center, Japan Aerospace Exploration Agency ABSTRACT = In the present study we developed a non-hydrostatic spectral microphysics cloud model and performed numerical experiments with the model to investigate the aero sol effect on a water cloud microphysics. Numerical model used for the experiments is a coupled model of non-hydrostatic d ynamical framework and spectral microphysics cloud model, both of which were new ly constructed in the present study. We consider a particle system composed by a erosols, liquid-phase particles and ice-phase hydrometeors of various species i. e. ice crystals, snowflake, graupel and hail, and explicitly calculate the evolu tion of their size distribution function in the spectral microphysics model. Numerical experiments were performed with this model to investigate the interact ion between aerosol and water cloud. It was found that the simulated correlation between cloud particle effective radius and optical thickness was consistent wi th those acquired by satellite observation. Cloud effective radius and optical t hickness are positively correlated when the cloud is not drizzling, contrary to negative correlation when the cloud is accompanied by drizzle-sized particles. A sensitivity experiment also showed that the correlation pattern is systematical ly modified by a change of aerosol amount, that is, cloud becomes to have smalle r particles and optically thicker with increasing aerosol amount. We also invest igated the dependence of cloud properties on column aerosol particle number obta ined from the simulation. Cloud particle effective radius and optical thickness was simulated to be negatively and positively correlated with column aerosol par ticle number, respectively, resulting an approximate constancy of Liquid Water P ath (LWP) independent of aerosol particle number because LWP is proportional to optical thickness multiplied by effective radius. These characteristics are qual itatively consistent with those reported from the statistics obtained by satelli te observation. Simulated column cloud particle number was roughly linear with c olumn aerosol particle number in log-log scale following the relationship NcåNa k with k=0.70. This value is close to those reported by past researches, althoug h the global statistics recently obtained by satellite observation provided smal ler value as k=0.50.