Multi-Pulse Corona Discharges in Thunderclouds Observed in Optical and Radio Bands

Area of Science:

• Atmospheric electricity
• Thunderstorm phenomena
• Optical and radio emissions

Background:

• The initiation of lightning within thunderclouds is not fully understood.
• Blue LUminous Events (BLUEs), optical signals from electrical corona discharges, are observed preceding lightning.
• The Atmosphere-Space Interactions Monitor (ASIM) provides new data on lightning initiation.

Purpose of the Study:

• To investigate the relationship between optical and radio emissions during thunderstorm events.
• To identify and characterize new types of electrical discharges.
• To differentiate between electrical discharges that lead to lightning and those that do not.

Main Methods:

• Combined optical and radio observations of a thunderstorm near Malaysia.
• Analysis of Blue LUminous Events (BLUEs) detected by the ASIM.
• Correlation of optical pulses with radio signals, including Narrow Bipolar Events (NBEs).

Main Results:

• A novel event with multiple optical and radio pulses was identified.
• The initial optical pulse correlated with a strong Narrow Bipolar Event (NBE).
• Subsequent optical pulses, occurring milliseconds later, showed weaker radio signals, suggesting horizontal discharges not leading to full lightning.

Conclusions:

• The study reveals a new type of electrical discharge in thunderstorms.
• Findings suggest that the characteristics of optical and radio pulses can distinguish between lightning-initiating and non-initiating discharges.
• This research contributes to a deeper understanding of the complex processes governing lightning formation.