The research and projection of regional and basin-scale precipitation change adaptable to water problems in Asia.

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Using two regional atmospheric models, some numerical experiments are performed in order to simulate changes of regional climate and water cycles in some river basins. First, we estimated the effect of global warming on the snow depth in the mountainous areas in Japan. After confirming the accuracy of hindcast simulations of snow depth by the hi-resolved numerical models, a dynamical downscaling is conducted for the future projection by Pseudo-Global-Warming method. This method reduces the uncertainty caused by the interannual variability and excludes the model biases in the present climatology reproduced by each GCM. Seasonal cycle of water balance is also simulated in a river basin in Japan. Second, We also investigated the relation between convective clouds and topography, ie., orography and the surface conditions including anthropogenic modification in Japan, China and Mongolia. The formation mechanism of the convective clouds is clarified. Third, this study focuses on the climatic change in early summer rainfall in East Asia (Mei-yu rainband). The numerical model well reproduces the change in the Mei-yu rainband over Southern China between the 1960s and the 1990s, suggesting that the climatic features of the Mei-yu rainband are well controlled by the climatic change in a large-scale circulation. Similarly, we clarify the regional climate systems around Tibetan Plateau and Mongolia. Finally, we analyzed perceptible water observed by the dense GPS network in Japan and clarified the moisture transport and cloud formation of clouds. Data assimilation of GPS perceptible water was also investigated in order to improve the accuracy of the short-term weather forecast.