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Nishi-Tokyo-shi, Japan

Miki T.,Japan Central Research Institute of Electric Power Industry | Saito M.,Japan Central Research Institute of Electric Power Industry | Sugimoto S.,Japan Central Research Institute of Electric Power Industry | Shindo T.,Japan Central Research Institute of Electric Power Industry | And 5 more authors.
IET Seminar Digest | Year: 2015

This paper describes observation of lightning currents at Tokyo Skytree, which is a 634-m high freestanding broadcasting tower stands in the eastern area of central Tokyo on Kanto Plain. Direct observation of lightning current by using a pair of Rogowski coils started in the end of February 2012, and high-speed cameras were set 6 months later. Both 19 downward and 23 upward lightning flashes were observed at Tokyo Skytree from 2012 to 2014. This paper reports on updated lightning parameters, such as current and charge transfer of return strokes of downward and upward lightning. This report also describes the relationship between occurrence of downward/upward lightning and meteorological conditions. The authors investigated their meteorological conditions by data assimilation with Numerical Weather Forecasting and Analysis System (NuWFAS) developed by CRIEPI, and obtained altitudes of -10°C temperature level, where the lower charge centre frequently exists in thunderclouds. During 2012 to 2014, downward flashes to the tower occurred when the altitude of -10°C temperature level was higher than 5.5 km except at 2 cases. In contrast, except at 3 case, upward flashes occurred when the -10°C temperature level was lower than 5.5 km. © 2015, Institution of Engineering and Technology. All rights reserved. Source


Saito M.,Japan Central Research Institute of Electric Power Industry | Shindo T.,Japan Central Research Institute of Electric Power Industry | Ishii M.,University of Tokyo | Taguchi H.,TOBU TOWER SKYTREE Co. | And 5 more authors.
IEEJ Transactions on Power and Energy | Year: 2015

Observation of lightning current by using Rogowski coils started in February 2012 at Tokyo Skytree, which is a 634-m high freestanding broadcasting tower. Electromagnetic field waveforms are also observed by capacitive antennas at several tens of kilometers from the tower. Simultaneously observed lightning current and electric field waveforms are reproduced by using an electromagnetic model of a return stroke on lossy ground with the help of NEC-4. Electromagnetic field waveforms are reproduced by using an inclined lightning channel reconstructed from observed images. It turns out that the electromagnetic field waveforms are considerably affected by lightning channel geometry and ground conductivity. © 2015 The Institute of Electrical Engineers of Japan. Source


Shindo T.,Japan Central Research Institute of Electric Power Industry | Miki T.,Japan Central Research Institute of Electric Power Industry | Saito M.,Japan Central Research Institute of Electric Power Industry | Asakawa A.,Japan Central Research Institute of Electric Power Industry | And 5 more authors.
IEEJ Transactions on Power and Energy | Year: 2015

Two types of lightning flashes, which are upward lightning and downward lightning, have been observed at Tokyo Skytree. Relationship between upward lightning occurrence and meteorological conditions has been investigated with the data obtained by Japan Meteorological Agency. It has been found that when the altitude of -10°C is lower than 6000 m, most of lightning flashes are upward and vice versa. © 2015 The Institute of Electrical Engineers of Japan. Source


Shindo T.,Japan Central Research Institute of Electric Power Industry | Miki T.,Japan Central Research Institute of Electric Power Industry | Saito M.,Japan Central Research Institute of Electric Power Industry | Tanaka D.,Japan Central Research Institute of Electric Power Industry | And 6 more authors.
IEEE International Symposium on Electromagnetic Compatibility | Year: 2014

Observation of lightning hitting Tokyo Skytree, a 634-m high freestanding broadcasting tower, started in February 2012. In 2012 and 2013, current waveforms associated with 24 lightning flashes have been obtained by specially designed wide-band Rogowski coils installed at a height of 497m. The ratio of upward lightning is quite different in 2012 and 2013. In addition to these, we have observed development of upward connecting leaders started from the top of Tokyo Skytree with a high-speed camera. © 2014 IEEE. Source


Miki T.,Japan Central Research Institute of Electric Power Industry | Saito M.,Japan Central Research Institute of Electric Power Industry | Shindo T.,Japan Central Research Institute of Electric Power Industry | Tanaka D.,Japan Central Research Institute of Electric Power Industry | And 5 more authors.
2014 International Conference on Lightning Protection, ICLP 2014 | Year: 2014

This paper describes observations of lightning current waveform at Tokyo Skytree, which stands in the eastern area of central Tokyo, located in the Kanto Plain, and is a 634-m high freestanding broadcasting tower. Direct observation of lightning current by using a pair of Rogowski coils started in the end of February 2012. From 2012 to the end of 2013, currents associated with 24 lightning flashes which hit the tower were recorded. In 2012, most of the flashes were upward as was expected; however, in 2013, most of the flashes observed in summer were downward. We have also evaluated statistical characteristics of obtained lightning current waveforms. © 2014 IEEE. Source

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