Multi-instrumental observation of an upward cloud-to-air discharge above a Mediterranean storm

On the night of November 1^st, 2022, a luminous discharge was produced above a storm over the northwestern Mediterranean Sea. An unprecedented set of optical and electrical data makes it possible to characterize this event. It is embedded in a lightning flash which starts with a positive discharge producing a high-power VHF source at 6 km followed by VHF sources at 10 and 4 km within the cloud. The luminous event above the cloud is identified as a negative leader emerging from the cloud and reaching 14.2 km, topped with streamers up to about 17.2 km, and followed by channel rebrightening phases connected to the negative charge of a positive dipole. It is preceded by a convective surge and a production of positive flashes within the same storm region. Its polarity and its triggering conditions show similarities with those of gigantic jets.