Inter-decadal changes in a subseasonal climate variability in the western North Pacific region with Northern Indian Ocean in boreal summer

It has been recognized that the low-tropospheric circulations associated with Northeast Asian and the western North Pacific monsoons are closely related to each other via atmospheric teleconnection in boreal summer. This teleconnection can be understood by the responses to the stationary Rossby wave. In addition, the climate mode including the atmospheric teleconnection has a large variability on inter-decadal as well as interannual time scales associated with adjacent climate variability. This study focuses subseasonal climate modes, which were decomposed by the self-organizing map (SOM) analysis. This study suggests that those modes are significantly increased in the last few decades, and the changes in the climate mode are related to upper ocean warming of Northern Indian Ocean due to global warming and changes in the climate variability in the Indian Ocean. This study also shows the possible reasons for the analysis results.