Gamma Ray Glow Observations at 20-km Altitude

Area of Science:

• Atmospheric physics
• Thunderstorm research
• Gamma-ray astronomy

Background:

• Thunderstorms produce energetic radiation, including gamma rays.
• Understanding these phenomena is crucial for atmospheric and astrophysical research.

Purpose of the Study:

• To investigate energetic radiation from thunderstorms and lightning.
• To analyze gamma-ray glow events observed over Colorado.
• To explore the cloud's charge structure and potential radiation production mechanisms.

Main Methods:

• An ER-2 aircraft campaign over the continental United States in spring 2017.
• Utilized a payload of instruments to detect optical signals, electric fields, and gamma rays.
• Analyzed two specific gamma-ray glow events using flight data, radar, and radio measurements.

Main Results:

• Observed gamma-ray glow events over Colorado on May 8, 2017.
• The thundercloud system exhibited strong convection.
• Electric field, radar, and radio data suggest an inverted charge structure (upper negative, lower positive).

Conclusions:

• The precise mechanism for gamma-ray glow production remains ambiguous.
• Possible mechanisms include local cosmic background enhancement by electric fields or enhancement within the cloud with a strong electric field.
• Further research is needed to definitively determine the gamma-ray production pathway.