This study uses Fast On-Orbit Detection of Transient Events (FORTE) satellite observations to identify superbolt-class optical lightning events and evaluate their origins. Superbolts have been defined by Turman (1977) as lightning pulses whose peak power exceeds 10 W. However, it has been unclear whether superbolts resulted from particular types of high-energy lightning process or whether they were the result of measurement bias. In the latter case, any decently-bright lightning process could be recorded as a superbolt if the sensor had a particularly clear sight line to the hot channel without thick clouds diluting the optical signals.

Our 12-year analysis of FORTE superbolt detections indicates that the lower superbolt energy range (~100 GW) is dominated by normal lightning, but brighter cases up to or exceeding the terawatt scale are predominantly strong +CG strokes that originate from specific types of storms. Oceanic storm systems, particularly during the winter, and especially those located around Japan are shown to produce these intense superbolts. We suggest that both interpretations of superbolt origins are correct: that some result from favorable viewing conditions and would not be identified as such by another instrument located elsewhere, and that others are associated with a unique set of physics that may merit the “superbolt” distinction.