Reanalysis of Global Soil Wetness and its Application to Numerical Rainfall Forecasting

全球气候系统、大气和降水模式都受到海表温度、土壤湿度和积雪等边界条件的影响，特别是土壤湿度及其异常的影响是近年来研究的热点。几年前开展的全球土壤湿度计划利用陆面模式为全球气候模式或全球水文模式提供了1987年和1988年土壤湿度的综合数据集。然而，仍然有可能改善这个数据集，并利用该数据集的影响研究是否降雨预报受土壤湿度的影响很大，作为这项研究的结果，在两年中，首先，一个国际建议称为全球土壤湿度计划1.5在国际社会的全球水文气候学。为此，提出了一种修正方法 ...更多信息 艾德增加了地球仪北方（较冷）冬季的降水量。其次，研究了全球土壤湿度项目（Global Soil Wetness Project）产品、卫星遥感土壤湿度数据、卫星土壤湿度数据（经全球土壤湿度项目（Global Soil Wetness Project）分析修正后的土壤湿度数据）、应用于热带气候模式的季节性降水预报。结果表明，基于全球土壤湿度项目分析的改进方法在利用遥感地表土壤湿度进行降雨预报方面具有很大的潜力。然而，基本上，土壤湿度的影响可能没有那么强，特别是在热带地区的海面温度相比。最后，考虑到全球土壤湿度项目序列中计算出的全球土壤湿度和径流量必然是世界本身的水资源，利用该项目的成果进行了全球水资源评价。除了从该项目的产品中获得的自然水资源外，还利用若干统计数据集和基于地理信息系统的数据集汇编了人类取水量。通过该框架可以得到当前全球0.5度缺水量的估计值，并可用于未来缺水量的评估。少

Global climate system, atmosphere and rainfall patterns have been know as to be critically much influenced by the underlying boundary conditions such as sea surface temperature (SST), soil moisture, snow and so on. In particular, the effects of soil moisture and its anomaly have been a matter of intensively investigated in these several years. The Global Soil Wetness Project which was carried out a few years ago provided a comprehensive dataset of soil moisture in 1987 and 1988 with the utilization of land surface models for global climate models or global hydrological models. However, there still remains possibility to improve this dataset and to utilize the dataset for the impact study whether rainfall forecasting is much affected by soil moisture or not.As a consequence of this research in two years, at first, an international proposal called Global Soil Wetness Project 1.5 is presented in the international community of global hydro-climatology. For it, a correction method is propos … More ed to improve precipitation amount in the northern (colder) part of the globe in winter. The new dataset with the improvement is constructed and can be open through internet.Secondary, the effects of soil moisture on rainfall simulation with a climate model were investigated.Three sets of soil moisture, the product of Global Soil Wetness Project, satellite derived soil moisture with remote sensing, satellite-based soil moisture but modified through the relationship found in Global Soil Wetness Project analysis, were applied to the seasonal rainfall forecasting with a climate model especially focusing on climate in the tropics. Results indicated that the modified method based on Global Soil Wetness Project analysis has great potential to utilized remotely sensed surface soil moisture for rainfall forecasting. However, basically, the impacts of soil moisture may not be so strong compared to sea surface temperature especially in the tropics. Further investigation and trial are indispensable.At last, considering that global soil wetness and runoff calculated in the sequence of global soil wetness project must be water resources in the world itself, global water resources assessment was conducted with the products of the project. In addition to the natural water resources derived from the products of the project, amounts of water withdrawal by human beings were compiled with several statistical and GIS-based datasets. A current estimates of water scarcity in the world at 0.5 degree basis was obtained through it. This framework can be utilized for possible assessment of expected future water scarcity. Less