Researcher's homepage		Cloud/Precipitation Process Group Clouds and precipitation play critical roles not only in severe storms, but also in climate change. It is necessary to resolve cloud systems in Regional Model (RM) and Global Circulation Model (GCM) to predict evolution of cloud systems and precipitation accurately. Our group has four major tasks, that is, (1) the investigation of the variability of the water cycle in east Asia and the role of meso-scale precipitating cloud systems, (2) the improvement of parameterization schemes of microphysical processes, (3) the development of a new cloud resolving meso-scale model, and (4) the development of the parameterization scheme of meso-scale cloud systems. Of course, these tasks should be done based on synthetic observations by artificial satellites, aircraft, research vessels, meteorological radars, etc. in collaboration with national and international institutions. Figure:Comparison of 3-D and 1-D radiative transfers for a cumulus cloud case. Black lines denote contours of cloud water content. Computations were made for a solar altitude of 30 degrees and near-infrared wavelength. The 3-D radiation model is based on Monte Carlo method and highly optimized for numerical efficiency on large-scale computers. It is clearly shown that the 1-D model does not simulate the solar direct beam effect and horizontal diffusion of multiply scattered lights. The 3-D model simulates enhanced heating at cloud tops. We are working on developments of accurate parameterizations and approximations of 3-D radiative transfer in order to realistically simulate these 3-D radiative effects in weather forecast models and climate models.