Abstracts for the 6th International GAME Conf.
3-5 December 2004
Kyoto Japan
Numerical study of the aerosol effect on water cloud optical properties with nonhydrostatic spectral microphysics cloud model
Kentaroh Suzuki (1), Teruyuki Nakajima (1), Takamichi Iguchi (1), Gorou Asanuma (4), Takashi Y. Nakajima (5)
(1) Center for Climate System Research, University of Tokyo
(4) NTT west Japan
(5) Earth Observation Research Center, Japan Aerospace Exploration Agency
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¢ēNa
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.
Submittal Information
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Center for Climate System Research, University of Tokyo | |
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4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 | |
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