Sprites and lightning observation system installed at ESRANGE, Kiruna

Activities of sprites and elves were first recorded in the west coast of Japan when a cold front passed over Japan by Tohoku University group in 1998. This fact strongly predicts occurrence of sprites and elves in other areas in wintertime, such as Northern Scandinavia where large positive CGs are occurring in wintertime. Once sprites and/or elves in the polar region are detected, it would be expected that many important phenomena are occurring: the interaction between the lightning-induced phenomena and the polar ionosphere/magnetosphere by electron density enhancement and by field-aligned current connection, high energy particle supply to the magnetosphere and so on. In order to conduct the sprites/elves imaging in the polar region, we improved an image-intensified CCD camera at ESRANGE, Kiruna, Sweden in August 2003, and also installed VLF receiver there. Further, we set up 2-components ELF receivers as the third station of the ELF world network of Tohoku University. All equipments are remotely controlled from Japan using network. A careful examination of Scandinavian lightning data provided by SINTEF and ELF recordings by Tohoku University shows there exist some strong cloud-ground discharges with a sufficient charge moment to produce sprites in January and February in the polar region.