Parental thunderclouds of sprites and elves in winter Japan
Abstract
We have conducted the observation campaign of sprites/elves in winter since December 1998. We use two observation sites with distance of ~300 km to make triangulation: Optical instruments and VLF wave receivers have been installed both at two observation sites. During the campaigns we succeeded in measuring sprites and elves with image-intensified CCD cameras, photometers and VLF receivers. Totally, 21, 2, and 11 sprites were recorded in each campaign, respectively. The elves were detected more frequently than sprites. During 2000/2001 campaign 26 elves appeared on single night. This might be due to large emission extent of elves in horizontal and the fact that elves could be caused by not only positive discharge but also negative one. The number of event is strongly dependent on the parental thundercloud activity and weather conditions above the observation site. In 1998/1999 campaign, we observed the sprites when the cold front was approaching to and collided with the west coast of Japan. The location of sprites determined by triangulation is just above the cloud in the cold front. The height of the cloud top is estimated to be 4-6 km and the width of the cloud is only 30 km. On the other hand, in the 20002001 campaign, sprites were observed above the Pacific Ocean ~500 km apart from the coast. Some of them are also associated with clouds at the cold front while some events appeared over the clouds detached from the cold front by >400km. The height of the cloud top are 5-7 km. Differences in dimensions and structures of sprites between in summer and in winter will be discussed in the point of view of the relationship to the characteristics of the parental cloud and discharges.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMAE31A0062T
- Keywords:
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- 0340 Middle atmosphere: composition and chemistry;
- 2435 Ionospheric disturbances;
- 3304 Atmospheric electricity;
- 3324 Lightning