Observation of sprites over the Asian continent and over oceans around Taiwan

Self Cite

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.

Section: Isual Sprites Produced By Positive and Negative Cg Strokesmentioning

confidence: 99%

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

Lu¹,

Cummer²,

Chen³

et al. 2017

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“…The first ever ground TLE campaign in Taiwan was conducted between April and August of 2001 as preparation work for the upcoming ISUAL experiment (Su et al 2002;Hsu et al 2003). The weather in Taiwan is heavily influenced in spring and summer by convective systems and typhoons.…”

Section: First Sprites Observed Over the Asian Continentmentioning

confidence: 99%

Selected results from the ISUAL/FORMOSAT2 mission

Hsu¹,

Su²,

Chen³

et al. 2017

Self Cite

The ISUAL (Imager of Sprites and Upper Atmospheric Lightning) is a scientific payload onboard the FORMOSAT2 satellite (FS2). This the first satellite project survey of global transient luminous events (TLEs) as one of the mission objectives. Since the ISUAL/FS2 launch in 2004, ISUAL has continuously monitored TLE occurrences over pre-midnight regions in the past ten plus years. As of December 2015, more than forty thousand TLEs, including the sub-species like elves, sprites, spritehalos, blue jets and gigantic jets, have been recorded from this space platform. In the meantime, as the supporting facilities to the space-borne ISUAL experiment, ground optical imagery systems have been deployed to observe TLEs occurring near Taiwan with several radio wave detection ground stations also installed to register lightningor TLE-related radio signals called sferics. From analyzing the observed events and the associated sferics, many TLE characteristics have been inferred. Among the most notable factors are the global distributions, the occurrence rates, and the charge injection and the energy impact to the upper atmosphere. In this article, the ISUAL payload, the auxiliary ground facilities and a few selected TLE survey results from the ISUAL mission are concisely presented.Article history:

“…Up to now, the TLE family includes sprites (Sentman et al 1995;Lyons 1996;Winckler et al 1996;Cummer et al 2006;Yang et al 2008;Savtchenko et al 2009;Lang et al 2010;Suzuki et al 2011;Boggs et al 2016;Peng et al 2017), elves (Emissions of Light and VLF perturbation due to EMP Sources) Barrington-Leigh et al 2001;Kuo et al 2007;Wu et al 2017), halos ), blue starters, blue jets and gigantic jets (Pasko 2003;Su et al 2003;Kuo et al 2009;Chou et al 2011;Yang and Feng 2012;Liu et al 2015b). Sprites are usually produced by intense lightning discharges and are observed between about 40 -90 km altitude above thunderstorms (Sentman et al 1995;Hardman et al 2000;Neubert et al 2001;Su et al 2002;Pinto et al 2004;Cummer et al 2006; Van der Velde et al 2006;Yang et al 2008Yang et al , 2013aYang et al , 2015Lu et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Sprite possibly produced by two distinct positive cloud-to-ground lightning flashes

Yang¹,

Lu²,

Liu³

et al. 2017

Transient luminous event (TLEs) observations have been conducted in mainland China since 2007, with a number of TLEs documented. This study analyzed a very unusual and unique positive sprite event, that may be produced jointly by two distinct positive cloud-to-ground lightning flashes (+CGs) occurring within a short time difference but with different locations separated by about 27 km. This observation is different from previous studies reporting that most of the sprites were triggered by a single +CG flash and its possible following continuous current. Detailed analysis on extremely low frequency (ELF) magnetic field shows that combined charge moment change (CMC) due to the two +CGs is smaller (~1478 C km) than those of the parent CGs for the other two sprites (1582 and 2134 C km, respectively) recorded over the same thunderstorm. The vertical extension and brightness of the sprites correspond well with the CMC of their parent CGs, namely, the larger the CMC value the brighter the sprite, and the larger the CMC value the larger the vertical extension. Negative lightning flashes dominated during the thunderstorm life cycle. The three sprites occurred during a time window in which both negative and positive flashes were active. The three sprites occurred over the thunderstorm stratiform region.