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Date: 12/19 (Thu)
Time: 14:45-16:30
Place: 8-1-03
Speaker: Shunsuke Niwa
Title:
Estimation of relationship between Typhoon intensity and electrical properties of Lightning

Abstract:
  Typhoon causes serious damage to human society every year. For reduction of risk of typhoon, it's important to predict typhoon track and intensity. According to Japan Meteorological Agency (JMA), typhoon track forecast is improving year by year but intensity forecast is not improving. Prediction of typhoon intensity is a big problem.

 Lightning is an good indicator of updraft intensity and typhoon is intensified by convection. Thus lightning can be use to monitoring typhoon intensity. Previous studies implied lightning activity in typhoon preceded typhoon intensity change about one day. However all previous studies used only lightning frequency. Electrical properties of lightning are also related to updraft intensity in thundercloud, so using electrical properties of lightning will help us to get more understand the connection between typhoon intensity and lightning activity.

  I researched the relationship between electrical properties of lightning and typhoon intensity for four typhoons, 201304 (weak), 201311 (strong), 201318(weak, large), 201326(strong, large). I set collect window (area to use lightning) as circle for inner core of typhoon and doughnut shape for rainband. I changed collect window size according to the size of typhoon.  I calculated peak current (Ip), charge moment change (CMC) and charge amount (Q) as electrical properties. After that I checked correlation coefficients (R)  between each property and Maximum sustained wind with taking lag. For this study, I obtained typhoon data from JMA, lightning data from World Wide Lightning Location Network (WWLLN) to determine lightning time and location, and Global ELF Observation Network (GEON) to calculate electrical properties. In this seminar, I would like to talk about results of analysis of mentioned 4 typhoons.
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