The ring current experiences dramatic enhancements during geomagnetic storms; however, understanding the global distribution of ring current energy content is restricted by spacecraft coverage. Many studies use ring current indices as a proxy for energy content, but these indices average over spatial variations and include additional contributions. We have conducted an analysis of Van Allen Probes' data, identifying the spatial distribution and storm‐time variations of energy content. Ion observations from the HOPE and RBSPICE instruments were used to estimate energy content in L‐MLT bins. The results show large enhancements particularly in the premidnight sector during the main phase, alongside reductions in local time asymmetry and intensity during the recovery phase. A comparison with estimated energy content using the Sym‐H index was conducted. In agreement with previous results, the Sym‐H index significantly overestimates (by up to ∼4 times) the energy content, and we attribute the difference to contributions from additional current systems. A new finding is an observed temporal discrepancy, where energy content estimates from the Sym‐H index maximize 3–9 h earlier than in‐situ observations. Case studies reveal a complex relationship, where variable degrees of agreement between the Sym‐H index and in‐situ measurements are observed. The results highlight the drawbacks of ring current indices and emphasize the variability of the storm time ring current.

中文翻译：

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挑战在地磁风暴中使用环形电流指标

在地磁风暴期间，环形电流会急剧增加。但是，了解环形电流能量含量的全球分布受到航天器覆盖范围的限制。许多研究使用环流指数作为能量含量的代表，但是这些指数是空间变化的平均值，并且包含其他贡献。我们对Van Allen Probes的数据进行了分析，确定了能量含量的空间分布和风暴时间变化。HOPE和RBSPICE仪器的离子观测值用于估算L中的能量含量‐MLT垃圾箱。结果表明，特别是在主要阶段的午夜时段，出现了较大的增强，同时在恢复阶段，本地时间的不对称性和强度也有所降低。使用Sym-H指数与估计的能量含量进行了比较。与先前的结果一致，Sym‐H指数显着高估了（最多约4倍）能量含量，并且我们将差异归因于其他当前系统的贡献。一个新发现是观察到的时间差异，其中Sym‐H指数估算的能量含量比原位观测值提前3–9 h。案例研究揭示了一个复杂的关系，在该关系中，观察到Sym-H指数与现场测量之间存在不同程度的一致性。