Daisuke Hasegawa, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan, Yoshinori Iizuka, Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan, Toshitaka Suzuki, Yamagata Univ, Yamagata, Japan, Hiroshi Ohno, Kitami Institute of Technology, Kitami, Japan and Shuji Fujita, Natl Inst Polar Research, Tokyo, Japan