|A Doppler radar|
Because the Doppler radar cannot get data without raindrops, it cannot measure water vapor content before it rains. The research team calculated the refractive index of air using the conditions of radio waves returning from transmission line towers and confirmed that the increase and decrease trend can be determined from the time change the refractive index. They put the trend together with such data as temperature and wind in the calculation model and reproduced the lightening storm that hit the Tokyo Metropolitan area on August 4, 2008 and found that the experimental data agreed with the actual rainfall. The research results are scheduled to be presented in the autumn meeting of Meteorological Society of Japan on November 21.
The torrential rainfall that hit Tochigi Prefecture
in the Kanto district on July 27, 2013