Study on the long distance transportation of acid snow and its effect on runoff processes

在该项目中，对琵琶湖北部的酸性雪进行了研究。在这项研究中，对运输、反应和沉积过程进行了物理和化学模拟。在此基础上建立了考虑酸性雪化学过程的云微物理模型。通过与水质观测结果的对比，对模型进行了验证。建立了由降雪、积雪、融雪、入渗过程组成的径流过程模型。最后通过与观测资料的对比，对模型进行了验证。酸雪数值模式的发展：在Oishi云模式的基础上发展了包含显式云微物理过程的云模式。然后我们诊断性地考虑了SOx和NOx的生成和沉积过程。结果表明，SOx和NOx的混合比比观测数据要大得多。因此，我们现在正在开发预测化学物质传输过程的模型。酸雪径流过程的模拟及其在流域尺度上的应用：在极小流域(5.4 km2)有重要的观测期和常规测量系统，可以制作酸雪径流过程模型。然后分别用水量模型、水质模型、混合模型和多层模型对考虑流域尺度的模型进行了应用。结果表明，冰雪融化的日变化、酸休克引起的pH值下降、河流pH值的日变化都能很好地解释这条河的日变化。

In the project, study on the acid snow in the northern part of the Lake BIWA has been done. In the study, transportation, reaction and deposition processes are modeled both physically and chemically. Then the cloud microphysics model that considers the chemical processes of acid snow has been developed. We verify the models by comparison with water quality observation. We also developed the model of runoff process which consists of snow fall, snow storage, snow melt, penetration processes. Finally we also verify the model by comparison with observed data.Development of the numerical model of acid snow : Cloud numerical model that includes the explicit type cloud microphysical processes has been developed based on cloud model made by Oishi. Then we consider the generation and deposition processes of SOx and NOx diagnostically. We obtained the result that the mixing ratio of SOx and NOx is quite bigger than observed data. Therefore, we are now in process of development of the model which prognosticate the chemical transportation processes. This model is one of the best models in the world since it can calculate the distribution of cloud droplet diameter that is very important factor for chemical processes.Modeling of Acid snow runoff process and its application to basin scale : We had the important observation period and routine measuring system in very small basin (5.4 Km^2) for making the model of acid snow runoff process. Then we made the application of the models for considering a basin scale by using a water quantity model, a water quality model, a hybrid model and a multi layer model. We obtained the result that the daily variation of snow melting, decreasing of pH by acid shock, daily variation of pH in the river is well explained.