Dancing Sprites Above a Lightning Mapping Array ‐ an Analysis of the Storm and Flash/Sprite Developments

One of the most enigmatic types of sprites is the dancing sprite which appears to dance above the storm as sequential luminous emissions a few 100 ms or less apart. Dancing sprites occur in relatively small proportion and many aspects of their generation remain unknown. We present a multi-instrumental analysis of a 20-hour duration Mesoscale Convective System (MCS) over the northwestern Mediterranean Sea on September 21, 2019, that produced 21 sprites recorded with a video camera, of which 19 (90) were dancing sprites. The asymmetric trailing stratiform MCS developed in strong convective conditions having a CAPE of 3,500 J . It formed several convective cores (up to 2,900 with cloud top temperature -C) and exhibited a bow echo structure during the sprite production period. Using Lightning Mapping Array data, we show that the sprite producing positive cloud-to-ground (SP+CG) flashes mainly initiated at the edge of the convective line on the side of the stratiform region. The flashes propagated 100-200 km across it, producing both positive and negative CG strokes. The 19 dancing sprite events included 49 sequences, of which 46 were associated with distinct SP+CG strokes and 3 with surges during the continuing current. An especially bright and wide sprite sequence was produced by three distinct SP+CG strokes that occurred within 3 ms and spread over 54 km. This sprite sequence could be classified as a new sprite category resembling a "wall" but structured in three groups, each associated with one of the +CG strokes.