Duration, spatial size and radiance of lightning flashes over the Asia-Pacific region based on TRMM/LIS observations

The geographical distributions of flash duration, length, footprint and radiance, as well as their correspondence with thunderstorm structures, are investigated for the first time in the Asia-Pacific region ranging from 70 degrees E to 160 degrees E and from 18 degrees N to 36 degrees N and in six specially chosen regions by employing flash data collected by the Lightning Imaging Sensor (LIS) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite and TRMM-based radar precipitation feature (RPF) data from 2002 to 2014. The flash length, footprint and radiance values are, on average, the largest over the deep ocean, followed by offshore waters and land. Flash duration is the longest over the offshore waters near the east coast of China, followed by the deep ocean and land. The Tibet Plateau and the northern part of the Indian Peninsula have the weakest flash properties in the study region. Furthermore, the geographic distributions of the flash properties exhibit evident seasonal changes. The monotonic relationship between flash spatial size and radiance is stronger than the monotonic relationships between flash duration and spatial size or radiance. Based on a comparison of the seasonal and regional changes in flash properties with RPF properties, convective intensity is proposed to play a crucial role in characterizing the flash spatial size and radiance, according to their inverse correlation in most regions. However, the climatological correspondence between flash duration and thunderstorm structures remains poorly constrained. We have launched a discussion of the possible association between thunderstorm structures and flash properties.