Storm time dynamics of ring current protons: Implications for the long‐term energy budget in the inner magnetosphere

Abstract Our investigation of the long‐term ring current proton pressure evolution in Earth's inner magnetosphere based on Van Allen Probes data shows drastically different behavior of the low‐ and high‐ energy components of the ring current proton population with respect to the SYM‐H index variation. We found that while the low‐energy component of the protons (<80 keV) is strongly governed by convective timescales and is very well correlated with the absolute value of SYM‐H index, the high‐energy component (>100 keV) varies on much longer timescales and shows either no correlation or anticorrelation with the absolute value of SYM‐H index. Our study also shows that the contributions of the low‐ and high‐ energy protons to the inner magnetosphere energy content are comparable. Thus, our results conclusively demonstrate that proton dynamics, and as a result the energy budget in the inner magnetosphere, do not vary strictly on storm time timescales as those are defined by the SYM‐H index.