• Instrumentation-driven, balloon/rocket campaigns established a multi-instrument approach to detect solar-terrestrial gamma-ray activity across energy ranges from tens of keV to >100 MeV, enabling cross-validation of bursts and associated ionization signals [1], [8], [9].

• Solar flare–ionosphere coupling is evidenced by ionospheric absorption proxies (riometers, VHF), SIDs, and cosmic-ray–induced ionization patterns, showing how solar events map into terrestrial high-energy signals [4], [15], [19], [6].

• Gamma-ray production mechanisms and spectroscopy across solar events are explored via collimation studies, bremsstrahlung detections, and energy-spectrum analyses, revealing instrument- and geometry-dependent signatures [5], [16], [14], [13], [11].

• X-ray observations linked to auroral activity and solar flares reveal bursts at 50–1000 keV (and higher) during high-altitude flights, highlighting a diverse phenomenology of atmospheric high-energy radiation [10], [17], [8], [19].