Monthly Accumulated Number of Flashes Observed by LIS
LIS observations show that the principal lightning activity is over the continents or the land rather than over the ocean. These lightning activities exit mainly in the summer hemisphere; over North American Continent in July and over Central Africa and South American Continent in January. Thunderstorm activity thus migrates with the seasons from the northern hemisphere to the southern hemisphere. There is little lightning activity over the desert, such as over the Sahara, as expected. However, the lightning activity over the Amazon, which is a tropical rainfall area, is surprisingly concentrated in the southern part. Additionally, there is a clear division between active and less active lightning regions along the Himalayas.
Lightning Activity over Australia
This image depicts lightning observed by the Lightning Imager Sensor(LIS) over Darwin, North Australia, with orange, yellow and blue dots. This was the beginning if the monsoon in this area, so there was much lightning. Lightning was observed over the Bathrust Island, Northern Territory, and the coast of the gulf of Carpentaria, where the famous Hector (the nick name of a large thundercloud, the cloud height of which sometimes reaches up to 20km) is found. The lightning over the coast of the gulf of Carpentaria was the most active. Lightning flashed mainly over the inland and the ocean coast. It seems that the inland lightning originates from the heat thunderstorm and the coastal lightning originates from the generation of thunderclouds due to the convergence of the sea and land breezes.
Lightning activity over western Japan during Baiu-Season
Lightning activity over western Japan during a late Baiu-Season observed by the Lightning Imaging Sensor (LIS) on board onthe Tropical Rainfall Measuring Mission (TRMM). Thunderstorms from July 2 through 4, 2000, were quite active all over Japan. Figure 1 presents the lightning activity captured by LIS as it passed over western Japan from 16:33 to 16:37 JST July 3. The active cumulonimbus clouds and lightning flash locations are found to be coincident. The cumulonimbus clouds seemed to develop along the Baiu front from Kyusyu district to the Kii Peninsula. An isolated thundercloud in Kanto area is also seen and lightning activity isnoticed there. LIS recorded 132 lightning flashes over 19 thunderclouds during these 4 minutes.
Lightning Distribution over Japan Islands and Pacific Ocean
Statistical lightning activity near Japan. The last two-year observations by LIS indicate that thunderstorms are active over land during summer and active over the Pacific Ocean during winter. The lightning activity seems to migrate with the season, and this is an interesting new result. Since it has been noticed that winter thunderstorms are active along the Hokuriku Coast and over the Sea of Japan, Fig. 3 presents a new discovery.