Analysis of lightning strokes associated with sprites observed by ISUAL in the vicinity of North America

• Main Authors: Gaopeng Lu, Steven A. Cummer, Alfred B. Chen, Fanchao Lyu, Dongshuai Li, Fei Liu, Rue-Ron Hsu, Han-Tzong Su
• Format: Article
• Language: English
• Published: Chinese Geoscience Union 2017-01-01
• Series: Terrestrial, Atmospheric and Oceanic Sciences
• Online Access: http://tao.cgu.org.tw/media/k2/attachments/v284p583.pdf

We examined the broadband (< 1 Hz to 30 kHz) lightning sferics associated with 395 sprites observed near North America by the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) onboard the FORMOSAT-2 satellite in a 12-year period from 2004 - 2015. Our analysis indicates that the ISUAL dataset contains a significant fraction (69, or ~18%) of negative sprites, which were predominantly (> 80%) observed over oceanic and coastal thunderstorms mostly in tropical areas. The mean and median of impulse charge moment change (iCMC) associated with positive (negative) sprites are +346 C km (-709 C km) and +280 C km (-649 C km), respectively. The morphology and parent lightning properties (e.g., typically with high peak currents > -80 kA and large iCMCs > -300 C km) of negative sprites observed by the ISUAL are generally consistent with that documented in ground-based observations, but the ISUAL dataset does imply that sprites are sometimes produced by negative strokes with sub-critical iCMCs (less than -300 C km). Consequently, the future survey of global occurrence of sprites is desired to be based on complementary ground and space-borne observations.