Abstract For detection of rather large ionospheric structures (such as high-latitude ionospheric troughs, main ionospheric trough, etc.) using Global Navigation Satellite Systems (GNSS) we suggest employing the analysis of anomalous deviations in behavior of the absolute slant total electron content (TEC) on particular “GNSS receiver - GNSS satellite” lines of sight (LOSs). Using data of four high-latitude GNSS-stations, the proposed method allowed us to detect the 5 May 2013 high-latitude ionospheric trough (HLIT), determine its location and size, and follow the dynamics. The HLIT was located on the dayside within 25-185°E. Initially (04:40–06:00 UT), the HLIT equatorial wall and bottom were within 68-78°N and 70-80°N, respectively. The trough northern wall was not registered at this time, most likely due to insufficient number of LOSs. During the next hour (06:00–07:00 UT), the trough has moved 2-4° southward. Its bottom lay near 68-76°N; equatorial and polar walls were within 67-74°N and 77-78°N, respectively. The trough width was about 4°. At 07:00–08:00 UT, the HLIT structure and location remained almost the same. To interpret the observation results, we used the model for ionosphere-plasmasphere coupling (developed at the Institute of Solar-Terrestrial Physics SB RAS) to simulate the high-latitude ionosphere conditions on 4–6 May 2013. This simulation showed that on 5 May 2013, a high-latitude trough was formed on the dayside at 40-200°E and 78-85°N. The most likely reason for the formation of HLIT both in model calculations and in reality was a change in the magnetospheric convection in the high-latitude ionosphere caused by the moderate geomagnetic disturbances (substorms) on 4–5 May 2013. The trough location determined from the analysis of anomalous TEC deviations on particular LOSs was in good agreement with location of the high-latitude ionospheric trough obtained from numerical simulation. Thus, the analysis of anomalous deviations in TEC behavior on particular LOSs expands the GNSS potential in detecting large-scale irregularities in the ionosphere.

中文翻译：

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使用 GNSS 检测高纬度电离层结构

摘要 为了使用全球导航卫星系统 (GNSS) 检测相当大的电离层结构（如高纬度电离层槽、主电离层槽等），我们建议采用绝对倾斜总电子含量行为的异常偏差分析（ TEC) 在特定的“GNSS 接收器 - GNSS 卫星”视线 (LOS) 上。使用四个高纬度 GNSS 站的数据，所提出的方法使我们能够检测 2013 年 5 月 5 日的高纬度电离层槽 (HLIT)，确定其位置和大小，并跟踪动态。HLIT 位于 25-185°E 的白天。最初 (04:40–06:00 UT)，HLIT 赤道壁和底部分别在 68-78°N 和 70-80°N 内。槽北壁此时未注册，很可能是由于 LOS 数量不足。在接下来的一个小时（世界标准时间 06:00–07:00），低谷向南移动了 2-4°。它的底部位于北纬 68-76°附近；赤道壁和极地壁分别在 67-74°N 和 77-78°N 之内。槽宽约为4°。在 07:00–08:00 UT，HLIT 结构和位置几乎保持不变。为了解释观测结果，我们使用电离层-等离子体层耦合模型（由日地物理研究所 SB RAS 开发）来模拟 2013 年 5 月 4-6 日的高纬度电离层条件。该模拟表明，5 月 5 日2013年，40-200°E和78-85°N日侧形成高纬槽。在模型计算和现实中形成 HLIT 的最可能原因是 2013 年 5 月 4 日至 5 日中度地磁扰动（亚暴）引起高纬度电离层磁层对流的变化。对特定 LOS 的异常 TEC 偏差的分析与从数值模拟获得的高纬度电离层槽的位置非常吻合。因此，对特定 LOS 上 TEC 行为的异常偏差的分析扩展了 GNSS 在检测电离层中的大规模不规则性方面的潜力。