  The Earth's ring current is highly dynamic and is strongly influenced by the
solar wind. The ring current alters the planet's magnetic field, defining
geomagnetic storms. In this study, we investigate the decay timescales of ring
current protons using observations from the Van Allen Probes. Since proton
fluxes typically exhibit exponential decay after big storms, the decay time
scales are calculated by performing linear regression on the logarithm of the
fluxes. We found that in the central region of the ring current, proton decay
timescales generally increase with increasing energies and increasing L-shells.
The ~10s keV proton decay timescales are about a few days, while the ~100 keV
proton decay time scale is about ~10 days, and protons of 269 keV have decay
timescales up to ~118 days. These findings provide valuable insights into the
ring current dynamics and can contribute to the development of more accurate
ring current models.
