Contribution of atmospheric circulation change to the 2012 heavy Rainfall in Southwestern Japan

Yukiko Imada, Masahiro Watanabe, Masato Mori, Masahide Kimoto, Hideo Shiogama, Masayoshi Ishii

Research output: Contribution to journalReview articlepeer-review

12 Citations (Scopus)


The southwestern part of Japan experienced an extraordinary heavy rainfall from 11 July to 14 July 2012. This event was record breaking at many sites and caused devastating damage. The stronger Pacific subtropical high (PASH) during the 2012 rainy season was characterized by a dominant teleconnection pattern over East Asia called the Pacific-Japan (PJ)pattern. A 100-member AGCM ensemble experiment (factual run, called the ALL run) by an atmospheric component model of the Model for Interdisciplinary Research on Climate version 5 (MIROC5). The model was integrated over the recent four years with observed SST and sea ice under the anthropogenic external conditions during the period. The PDFs of both ALL and NAT runs are shifted to the positive PJ pattern relative to the climatological distribution (green). On the other hand, the difference between the ALL and NAT runs is subtle and an ensemble mean of the ALL run is slightly larger than that of the NAT run. The extremeness of the Japanese heavy rainfall of 2012 was mainly caused by the oceanic natural variability and probabilistic atmospheric natural variability rather than by anthropogenic climate change.

Original languageEnglish
Pages (from-to)S52-S54
JournalBulletin of the American Meteorological Society
Issue number9
Publication statusPublished - Sept 1 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science


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