Global Hydrology

The energy which drives the earth-system is the radiation from the sun, and the water circulation plays an important role in circulation and distribution of the energy. The objective of this field is understanding the water circulation on the earth.

The researches of our laboratory about this field are divided into three subjects bellow; (1)water budget in climate-system, (3)analyses using satellite data, and (2)numerical climate modelling. The international project which our laboratory concerned with is GAME (GEWEX Asian Monsoon Experiment ---one of the subprojects of GEWEX (Global Energy and Water Cycle Experiment))

Water budget in climate-system

The topic of this section is river water on the earth. The volume of the land water is very small compared with water all around the earth, and furthermore, most of the land water is in glacies or ices. Therefore, the amount of fresh water in rivers is very small. However, the circulation rate of river water is very high, and for that reason, the amount of water transportation by rivers is not small. Furthermore, freshwaters from rivers has great influences on ocean currents. Therfore, the role of river water circulation is very important in the global climate-system.

Analyses using satellite data

For the purpose of understanding and predicting the climate-system, it is necessary to know the present condition. Therefore, it is indispensable to obtain the global data reguraly. However it is difficult to obtain whole global data merely by ground observations. In this context, observations using satellite data have begun to attract attention. In order to increase the efficiency of using satellite data, validation with ground observation data and with GCM(General Circulation Model) have been performed.

Numerical climate modelling

Numerical climatic models are used for deeper understanding of the climate-system, and for prediction of the future climate and water resources. They are composed of physical-based equations,and meteorological components (such as temperature, wind velocity, and the volume of evapotranspiration and so on...) are obtained by integration of these equations from certain initial conditions. A climatic model is composed of four sub-models; Atmospheric General Circulation Models, Oceanic General Circulation Models, and Land Surface Models. To understand the whole climate-system, understanding interactioms between these each sub-systems is important. From that point of view, researches about interaction especially between the atmosphere and the land have been performed in the laboratory.