1. Department of Applied Chemistry, Faculty of Science, Science University of Tokyo, 1-3 Kagurazaka, Shinjukuku, Tokyo 162, Japan, Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464, Japan, and National Institute of Polar Research, 1-9-10, Kaga, Kitaku, Tokyo 114, Japan