The Asian monsoon is a dominant feature of climate in a broad region covering East Asia, Southeast Asia and South Asia, Japan included.
The Asian monsoon is represented by changes of prevailing winds from summer to winter which accompany changes of distribution of precipitation (rainfall and snowfall). In Japan, it is manifested as the contrast of weather patterns between Baiu (early summer rainy season) and the winter northwest monsoon. Precipitation is concentrated in the summer monsoon season in most of the region, and in the winter monsoon season in some areas such as the part of Japan facing the Sea of Japan. The Asian monsoon region also has tropical cyclones, which brings damages to human societies through flood and storm wind.
On the other hand, precipitation by monsoon and tropical cyclones plays a great role as water resources which sustain various agricultural activities including rice cultivation and thus more than 60% of the world’s population living in high density in the Asian monsoon region.

It is important for the people who live in the Asian monsoon region to cope with flood and drought under anticipated climate change and to enhance capability for efficient use of water resources. To achieve these goals, we collect hydroclimate observation data, and study variation and changes hydrological cycle associated with the Asian monsoon in both long and short time scales. More specifically, our activities are as follows.

To clarify patterns of heavy rainfall in Southeast Asia and patterns of large-scale meteorological fields which bring them.

To clarify long-term variability of climate, including tropical cyclone distribution over the Western North Pacific, and its cause.

To clarify long-term variability of heat and water balance in East and Southeast Asia and to assess accuracy of satellite data about them, in particular, solar radiation.