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

利用两个区域大气模式进行了数值试验，模拟了部分流域的区域气候和水循环变化。首先，我们估算了全球变暖对日本山区积雪深度的影响。在验证了高分辨率数值模式后预报雪深预报的准确性后，利用拟全球变暖方法对未来的雪深预报进行了动力降尺度分析。该方法减少了年际变化引起的不确定性，并排除了由每个GCM再现的当前气候学中的模型偏差。在日本的一个流域也模拟了水平衡的季节循环。其次，我们还研究了日本、中国和蒙古的对流云与地形、地形以及包括人为改造在内的地面条件的关系。阐明了对流云的形成机制。第三，研究了东亚初夏降水(梅雨雨带)的气候变化。数值模式较好地模拟了20世纪60年代至90年代中国南部梅雨雨带的变化，表明大尺度环流中梅雨雨带的气候特征受气候变化的很好控制。类似地，我们明确了青藏高原和蒙古周围的区域气候系统。最后，对日本密集GPS网观测到的可感水进行了分析，阐明了云的水汽输送和云的形成。为了提高短期天气预报的精度，还研究了GPS可感水的同化。

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.