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

  • Author(s): Jing Yang, Gaopeng Lu, Ningyu Liu, Mitsuteru Sato, Guili Feng, Yu Wang, and Jung-Kuang Chou
  • DOI: 10.3319/TAO.2016.07.22.01
  • Keywords: Positive sprites, Two distinct lightning flashes, Thunderstorm structure, ELF magnetic field
  • Sprites may be produced by two distinct +CGs
  • New observational fact for sprite production
  • CMC of parent CG correspond well with sprite extension and brightness

Observations oftransient luminous events (TLEs) have been conducted in mainland China since 2007, and a number of TLEs have been documented. In this study, we analyzed a very unusual and unique positive sprite event, which may be produced jointly by two distinct positive cloud-to-ground lightning flashes (+CGs) occurring with short time difference but with different locations separated by about 27 km, 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 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, and the three sprites occurred during a time window in which both negative and positive flashes were very active. The three sprites occurred over the thunderstorm stratiform region.

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