Shin-ichi Takehiro Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan e-mail: takepiro@geo.kyushu-u.ac.jp
Masaki Ishiwatari Graduate School of Environmental Earth Science, Hokkaido University Sapporo, Kita-ku, 060-0810, Japan e-mail: momoko@ees.hokudai.ac.jp
Kensuke Nakajima Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan e-mail: ken-suke@deepconv.geo.kyushu-u.ac.jp
Yoshi-Yuki Hayashi Graduate School of Mathematical Sciences, University of Tokyo 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8914, Japan e-mail: shosuke@ms.u-tokyo.ac.jp