Evolution of electron "zebra stripes" in the South Atlantic Anomaly: Initial observations from Macao Science Satellite-1

"Zebra stripes" denote banded structures characterized by periodic peaks and valleys in the spectrograms of energetic electrons in the Earth's inner radiation belt and slot region. In contrast to previous investigations primarily grounded in equatorial observations, this study presents two events exhibiting the evolution of electron zebra stripes within the South Atlantic Anomaly, as observed from the Macao Scientific Satellite-1 in low Earth orbit. Our findings affirm that the structural and evolutionary features of zebra stripes in both events accord with the drift echo hypothesis. The start time extrapolated from the electron spectrograms correlates with substorm onsets, consistent with prior conclusions. Notably, the duration of zebra stripe evolution during the event of June 5-6, 2023, reaches an impressive 34.7 h, a markedly longer interval than findings from the Van Allen Probes. This discrepancy suggests that the observed lifetime of electron zebra stripes may not inherently reflect natural limitations but could be constrained by instrumental capabilities. The results implicate that high-energy-resolution detectors have the potential to significantly enhance our capacity to scrutinize the dynamics of the radiation belt.