Themes of Our Research

@Predictability of climate during one month to several seasons is studied in our laboratory. Atmospheric state in such a long term can not be determined by its initial state only, because of its stochastic nature, and is largely affected by state of ocean and land which are lower boundary condition to atmosphere and are changed more slowly. We develop Atmospheric(-land)-Ocean coupled Global Circulation Model (AOGCM) and construct seasonal prediction system including the AOGCM in order to study predictability of monthly to seasonal climate.

@El-Nino phenomena lately attracted social attention occurs around the equator in the pacific ocean and the influence reaches around Japan, several thousand kilometers apart. Recent studies clarified that this phenomena is essentially based on a strong interaction between the atmosphere and the ocean in the tropic (ENSO), therefore AOGCM is an indispensable tool to deepen our understanding the phenomena and to improve quality of seasonal prediction in the tropic and east Asia.

@After El-Nino appeared in the tropic, it tends to become warm winter in Japan. However, it occasionally comes cold winter even though after El-Nino. In boreal winter, jet stream in the upper troposphere lies northward of Japan and the zonal stream occasionally meandered to the northern-southern direction. Siberian cold air is transported in a southward direction along with the curved jet stream and it causes cold Japanese winter. It is important question what dominates this variation of mid to high latitude atmosphere, and influences of Arctic sea ice, snow cover on the Eurasian Continent, and atmospheric state in the stratosphere are also to be explored.