A role of the Asian Monsoon system on the rainfall climatology during warm season in Japan

A role of the global-scale Asian Monsoon on the rainfall climatology around the Japan Islands (excluding that in Hokkaido) during warm season were discussed by reviewing the previous studies including the original results by the present author. Not only the mean monthly rainfall amount but also its year-to-year variation is large from June to September (or October) there. While the rainfall amount and its variation are especially large in the Baiu season in Kyushu, they relatively large in autumn rainfall season (so-called the "Akisame" or "Shurin" in Japan) . It is noted that the huge northward moisture transport from the moisture-rich subtropical high area to the Baiu frontal zone is largely affected by the low pressure area in the subtropical region around South Asia. On the other hand, the low pressure area associated with the stagnation of typhoons around the Southwest Islands area (to the southwest of the Japan Islands) seems to play an important role in the huge moisture transport toward the japan Islands in the autumn rainfall season. A comment on seasonal persistency of the rainfall anomaly from spring to summer and summer to autumn is also presented by examining the monthly rainfall data in Nagoya, the central part of the Japan Islands.

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