Katsuya Toyama, Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan, Hisashi Ono, Meteorological Research Institute, Japan, Naohiro Kosugi, Meteorological Research Institute, Tsukuba, Japan, Hiroyuki Tsujino, Meteorological Research Institute, Tsukuba, Ibaraki, Japan and Masao Ishii, Meteorological Research Institute, Ibaraki, Japan