- 著者
- Akira HUZITA
- 出版者
- Society of Geomagnetism and Earth, Planetary and Space Sciences
- 雑誌
- Journal of geomagnetism and geoelectricity (ISSN:00221392)
- 巻号頁・発行日
- vol.18, no.3, pp.363-372, 1966-12-20 (Released:2010-03-12)
- 参考文献数
- 18
- 被引用文献数
- 2 3
The effect of radioactive fallout upon the electrical conductivity of the lower atmosphere has been studied. The records of atmospheric conductivity which were made at the Geophysical Institute of Kyoto University in the period from 1961 to 1963 were compared with the records of the observation of fallout made in the same period at the Radiation Centre of Osaka Prefecture. The radioactive fallout, which originated from the large scale nuclear test explosion of 50 Mega ton class carried out by the U. S. S. R. at Novaya Zyemlya on October 30, 1961, caused a temporary increase in atmospheric conductivity up to the value twice as high as the normal value. The increase in conductivity was caused mainly by radiations from the dry fallout accumlated on the ground surface, which was estimated to have exceeded 250mμCi/m2 at that time. On the other hand, radiations from the airborne nuclear debris, the concentration of which reached as high as 120μμCi/m3 at that time, were considered to have contributed little to the increase in conductivity.
- 著者
- Heikki Nevanlinna
- 出版者
- Society of Geomagnetism and Earth, Planetary and Space Sciences
- 雑誌
- Journal of geomagnetism and geoelectricity (ISSN:00221392)
- 巻号頁・発行日
- vol.47, no.10, pp.953-960, 1995-10-20 (Released:2007-04-03)
- 参考文献数
- 26
- 被引用文献数
- 7 15
Systematic naked eye sightings of northern lights started in Finland in 1748. Such observations were carried out for about 100 years at two places in Southern Finland. All observations were compiled and published by Hällström (1847). Auroral occurrence frequencies in this compilation obey well the semiannual variation and the 11-year sunspot cycle when compared with other coeval auroral and magnetic data available in Europe. In the middle of the 100-year auroral series there was an anomalous period of very low auroral occurrence, known as Dalton's solar activity minimum, lasting about three decades from 1795 to 1825. As a signature of Dalton's minimum, auroras were totally absent from the sky in Southern Finland for the 10 years 1806-1815.