DataSheet1_The evolving paradigm of the subauroral geospace.PDF

An assessment of the status quo of fast subauroral flows—subauroral ion drifts (SAID) and subauroral polarization streams (SAPS), is presented. For a few decades, their development has been interpreted in terms of the voltage and current magnetospheric generators based largely on the drift motion of test particles. Recent multispacecraft observations revealed serious flaws in the generator paradigm and called for a new generation mechanism of fast-time subauroral flows and ring current (RC) injections. A novel model includes them in the overarching problem of the penetration of magnetotail plasma flow bursts (MPFs) into the plasmasphere and the substorm current wedge (SCW) development. SAID are created near the plasmapause, where inbound MPFs are short-circuited by the cold plasma. This stops the MPF’s electrons and forms the “dispersionless” plasma sheet (PS) boundary. The SAID electric field—the inherent part of the short-circuiting loop—stops the inward-moving MPF’s ions. In turn, SAPS are an integral part of the two-loop SCW system, or SCW2L, where the downward (R2) current emerges in response to the upward (R1) current in the SCW’s “head.” The meridional Pedersen current, which connects the R1 and R2 currents, leads to SAPS that ultimately drive the fast-time RC injections on the duskside.

本文针对快速亚极光区流——包括亚极光离子漂移（subauroral ion drifts, SAID）与亚极光极化流（subauroral polarization streams, SAPS）——的研究现状展开评估。数十年来，学界主要基于试验粒子的漂移运动，以电压与电流磁层发电机理论阐释这类流的演化机制。近年来的多航天器观测结果揭示了该发电机范式存在的严重缺陷，亟需提出新一代快速亚极光区流与环电流（ring current, RC）注入的生成机制。一项全新的模型将这类现象纳入磁尾等离子体流突发（magnetotail plasma flow bursts, MPFs）渗透入等离子体层、亚暴电流楔（substorm current wedge, SCW）演化这一整体研究框架中。SAID形成于等离子体层顶附近，此处入射的MPFs会被冷等离子体短路，该过程会阻滞MPFs中的电子，并形成无色散等离子体片（plasma sheet, PS）边界。作为短路回路的固有组成部分，SAID电场会阻滞向内运动的MPFs离子。而SAPS则是双回路SCW系统（记为SCW2L）的核心组成部分，该系统中向下的R2电流会响应SCW“头部”处向上的R1电流而产生。连接R1与R2电流的子午向佩德森电流会驱动SAPS，最终在黄昏侧引发快速环电流注入事件。