Thunderstorm and Lightning Activities over Western Pacific, Northern Indian Ocean and South China Sea Along with Their Adjacent Lands

Abstract

: The Lightning Imaging Sensor (LIS) and Radar Precipitation Feature (RPF) data are used to investigate the activities and properties of lightning and thunderstorms over a region including the Western Pacific, northern Indian Ocean and the South China Sea along with their adjacent lands. The lands feature significantly more frequent lightning flashes and thunderstorms than the oceans, especially the open oceans. The highest densities of lightning and thunderstorm occur over the Strait of Malacca and the southern foothills of the Himalayas. Over the ocean regions, the Bay of Bengal and the South China Sea are characterized by relatively frequent lightning and thunderstorm activities. Larger average spatiotemporal size and optical radiance of flashes can be found over the oceans; specifically, the offshore area features the most significant flash duration, and the open ocean area is characterized by the greatest flash length and optical radiance. The smallest average values of flash properties can be found over and around the Tibetan Plateau (TP). The oceanic thunderstorms tend to have a significantly larger horizontal extent than the continental thunderstorms, with the former and latter having the average area of the regions with radar reflectivity larger than 20 dBZ, generally over 7000 km 2 and commonly below 6000 km 2 , respectively. The TP thunderstorms show the smallest horizontal extent. Meanwhile, the oceanic thunderstorms exhibit greater 20 dBZ but smaller 40 dBZ top heights than the continental thunderstorms. The average flash frequency and density of the oceanic thunderstorms are typically less than 5 fl min –1 and 0.3 fl 100 km –2 min –1 , respectively; in contrast, the corresponding values of continental thunderstorms are greater. It is explored that the regions associated with strong convective thunderstorms are more likely to feature small-horizontal-extent and low-radiance flashes.