南极上空的弱STEVE会干扰导航卫星信号
A quiet STEVE disturbs navigation satellites' signals in the Antarctic
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中文总结 AI 辅助
研究首次发现南极地磁平静条件下的弱STEVE事件会产生等离子体不规则体，干扰GNSS信号，凸显了平静空间天气下卫星导航系统的潜在脆弱性。
中文摘要 AI 辅助
强热发射速度增强（STEVE）是一种发生在极光卵赤道侧的窄光学现象，与强烈的亚极光等离子体流和热层加热相关。尽管这些条件可能产生等离子体不规则体，但迄今为止，在地磁平静条件下STEVE对无线电波传播影响的直接证据尚未被观测到。本文首次报告了在地磁平静条件下在南极上空观测到的一次STEVE事件，并表明它产生了可测量的全球导航卫星系统（GNSS）信号波动。利用来自两个南极站点的协同光学观测和高分辨率（50Hz）GNSS闪烁测量，我们识别出与GNSS信号路径和STEVE弧相交同时发生的增强相位和振幅闪烁。观测结果表明存在等离子体不规则体，并显示光学结构的视高度存在显著时间变化（垂直运动范围为130-270公里）。我们发现，即使是相对较弱的STEVE事件，在没有重大地磁扰动的情况下也能影响GNSS信号传播，这扩展了之前将此类影响主要与地磁暴和强烈极光活动相关的研究。这一发现加深了对STEVE地球物理影响的理解，并强调了在看似平静的空间天气条件下，基于卫星的导航系统存在潜在脆弱性。该STEVE事件发生在南极海岸附近，而该区域的科学考察和航海船只严重依赖精确定位，这表明在亚极光区域原本平静的地磁条件下评估GNSS性能时，应考虑与STEVE相关的等离子体结构。
英文摘要
Strong Thermal Emission Velocity Enhancement (STEVE) is a narrow optical phenomenon that occurs equatorward of the auroral oval and is associated with intense subauroral plasma flows and thermospheric heating. Although these conditions can produce plasma irregularities, direct evidence of STEVE effects on radio wave propagation during geomagnetically quiet conditions has so far not been observed. Here we report for the first time a STEVE event observed over Antarctica during quiet geomagnetic conditions and show that it produced measurable fluctuations in the Global Navigation Satellite System (GNSS) signals. Using coordinated optical observations and high-resolution (50 Hz) GNSS scintillation measurements from two Antarctic stations, we identify enhanced phase and amplitude scintillation coincident with intersections between GNSS signal paths and the STEVE arc. The observations indicate the presence of plasma irregularities and suggest substantial temporal variations in the apparent altitude of the optical structure (vertical motion within the 130-270 km range). We find that even a relatively weak STEVE event can affect the GNSS signal propagation in the absence of major geomagnetic disturbances, extending previous studies that associated such effects primarily with storms and intense auroral activity. This finding expands the understanding of STEVE's geophysical impact and highlights potential vulnerabilities in satellite-based navigation systems during seemingly benign space weather conditions. The fact that this STEVE event occurred just off the Antarctic coastline, where scientific expeditions and seagoing vessels rely heavily on precise positioning indicates that STEVE-related plasma structuring should be considered in assessments of the GNSS performance under otherwise quiet geomagnetic conditions in subauroral regions.
