Controlling synoptic-scale factors for the distribution of transient luminous events

From analyzing the distribution of the transient luminous events (TLEs) registered by the Imager of Sprites and Upper Atmospheric Lightning payload on the FORMOSAT-2 satellite, we deduced the synoptic-scale factors that control the occurrence of TLEs. For the low-latitude tropical regions (25S ∼ 25N), 84% of the TLEs were found to occur over the Intertropical Convergence Zone and the South Pacific Convergence Zone and exhibited a seasonal variation that migrates north and south with respect to the equator. For the midlatitude regions (latitudes beyond 30), the occurrence of TLEs congregated over the Pacific Ocean, the Atlantic Ocean, and the Mediterranean Sea during the winter seasons. From studying the distributions of the daily winter storm centers and the winter TLEs, the winter TLEs are usually found to occur near the cold fronts and thus are closely related to the winter storms. Our study shows that 88% of the northern winter TLEs and 72% of the southern winter TLEs occurred near the midlatitude cyclones. The winter TLE occurrence density and the storm-track frequency share similar trends with the distribution of the winter TLEs offset by 10-15. Additionally, this study compares the luminous intensities of elves and sprites from the tropical and winter midlatitude regions. The results show that the convective systems in the tropical regions are presumably more capable of producing bright TLEs in comparison to their winter counterparts.