Abstract
The Maido-1 satellite observed the lightning discharges from February to October, 2009. We analyzed the observational results with the Maido-1 satellite above Southeast Asia area and the Atlantic Ocean area. First we calculated the change of the pulse width with the electromagnetic wave propagation in the ionosphere. The numerical calculation indicates that the full width at half maximum (FWHM) is changed by the incident angle to the ionosphere. The FWHM increases to tens of nanoseconds through the ionosphere. Next we compared the pulse widths of the received pulses by the Maido-1 satellite in the Atlantic Ocean area and Southeast Asia area. The results in the Atlantic Ocean area have the greater FWHM than those in Southeast Asia area. On the other hand, the results of World Wide Lightning Location Network (WWLLN) indicate that the distance between the position of the radiation source and the observation site in the Atlantic Ocean area is longer than in Southeast Asia area. The calculation results can explain two observational results (the maido-1 satellite and the WWLLN). Then we discussed the relationship between the number of the received pulses and the lightning activity level. From the analysis of the detected number by the WWLLN and the received pulse number by the Maido-1 satellite, the more active the lightning discharges are, the more VHF pulses are radiated.
