1. Research Center for Advanced Science and Technology University of Tokyo Tokyo Japan
2. Now at Department of Applied Chemistry, Tokyo Metropolitan University, Tokyo, Japan.
3. Decision and Information Sciences Division Argonne National Laboratory Argonne Illinois USA
4. International Institute for Applied Systems Analysis Laxenburg Austria
5. Space Monitoring Centre, Institute of Solar‐Terrestrial Physics Siberian Division, Russian Academy of Sciences Irkutsk Russia
6. Now at Exicom Technologies, Porirua, New Zealand.
7. Limnological Institute Siberian Branch, Russian Academy of Sciences Irkutsk Russia