In the ring current dynamics, various loss mechanisms contribute to the ring current decay, including losses to the upper atmosphere through particle precipitation. This study implements the field line curvature (FLC) scattering mechanism in a kinetic ring current model and investigates its role in precipitating ions into the ionosphere during the 17 March 2013 storm. Simulation results indicate that (1) the FLC scattering process exerts on energetic ions on the nightside where the magnetospheric configuration is more stretching. It is more effective on heavy ions (e.g., O⁺). These ion losses thereafter lead to a faster recovery of the ring current. (2) The FLC‐associated ion precipitation mainly occurs in the outer region (L > 5 for protons and L > 4.5 for oxygen ions) on the nightside. The O⁺ precipitation takes places in a wider region than protons although its intensity is much lower. Comparisons with POES observations suggest that more proton precipitation is needed in the inner region. This is probably caused by the less stretched configuration in the simulation that prevents more precipitation. It may also imply that other loss process is required in the model such as wave‐particle interactions. (3) The storm time precipitating proton flux of tens of keV due to the FLC scattering sometimes becomes comparable to that of electrons on the nightside, although electrons usually dominate the ionospheric energy deposition from the midnight eastward toward the dayside. (4) The FLC scattering process seems to be capable of explaining the formation of isotropic boundary in the ionosphere during the investigated event.

中文翻译：

---

场线曲率（FLC）散射对环电流动力学和各向同性边界的影响

在环电流动力学中，各种损耗机制都会导致环电流衰减，包括通过粒子沉淀对高层大气的损耗。这项研究在动力学环流模型中实现了场线曲率（FLC）散射机制，并研究了其在2013年3月17日风暴中将离子沉淀到电离层中的作用。仿真结果表明：（1）FLC散射过程在磁层结构更易拉伸的夜晚施加在高能离子上。它对重离子（例如O ⁺）更有效。此后这些离子损失导致振铃电流的恢复更快。（2）与FLC相关的离子沉淀主要发生在夜间的外部区域（质子L> 5，氧离子L> 4.5）。O ⁺尽管降水强度比质子低得多，但它发生在比质子更宽的区域。与POES观测值的比较表明，内部区域需要更多的质子沉淀。这可能是由于模拟中拉伸配置的减少，从而阻止了更多的降水。这也可能暗示模型中需要其他损失过程，例如波粒相互作用。（3）尽管电子通常从午夜东向白天向电离层能量沉积起主导作用，但由于FLC散射而使几十keV的质子通量沉淀的暴风雨时间有时与夜晚的电子可比。（4）FLC散射过程似乎能够解释在研究事件期间电离层中各向同性边界的形成。