Climate variability and change, Extreme weather, Climate dynamics, Air-sea interaction
We study large-scale climate variability in light of its regional and global impacts, mechanisms and predictability, through analyses and dynamical diagnoses of observational data, idealized numerical models, more sophisticated atmospheric general circulation models and climate models. We have mainly worked on worldwide impacts and mechanisms of teleconnections associated with tropical climate variability. Specifically we are studying several teleconnection patterns that induce extreme hot and cool summers to East Asia, in terms of their mechanisms, predictability, and slow modulations due to natural multidecadal variability and human-caused climate changes. Tropical ocean-atmosphere coupled variability such as El Niño/La Niña drives one of these teleconnection patterns, bringing predictability of summer climate in Japan a few months ahead. We have also shown that global influence of slow natural variability in the tropical Pacific can offset the human-caused global surface temperature rise for a decade or two, explaining the recent global-warming “hiatus” quantitatively. Our interests further expand to pattern formation mechanisms of global warming, and sea-ice variability in polar region with application to associated teleconnections.
1. Kosaka, Y. and S.-P. Xie: The tropical Pacific as a key pacemaker of the variable rates of global warming. Nature Geosci, 9, 669-673, 2016.