Ionospheric irregularities can affect satellite communication and navigation by causing scintillations of radio signals. The scintillations are routinely measured using ground-based networks of receivers. This study presents observations of ionospheric irregularities by Langmuir probes on the Swarm satellites. They are compared with amplitude scintillation events recorded by the Global Positioning System-Scintillation Network and Decision Aid (GPS-SCINDA) receiver installed in Mbarara (Lat: $$0.6^{\circ }\hbox {S}$$ 0 . 6 ∘ S , Lon: $$30.8^{\circ }\hbox {E}$$ 30 . 8 ∘ E , Mag. lat: $$10.2^{\circ }\hbox {S}$$ 10 . 2 ∘ S ). The study covers the years from 2014 to 2018 when both data sets were available. It was found that the ground-based amplitude scintillations were enhanced when Swarm registered ionospheric irregularities for a large number of passes. The number of matching observations was greater for Swarm A and C which orbited at lower altitudes compared to Swarm B. However, some counterexamples, i.e., cases when in situ electron density fluctuations were not associated with any observed L-band amplitude scintillation and vice versa, were also found. Therefore, mismatches between observed irregularity structures and scintillations can occur just over a few minutes and within distances of a few tens of kilometers. The amplitude scintillation strength, characterized by the S 4 index was estimated from the electron density data using the well-known phase screen model for weak scattering. The derived amplitude scintillation was on average lower for Swarm B than for A and C and less in accordance with the observed range. Irregularities at an altitude of about 450 km contribute strongly to scintillations in the L-band, while irregularities at about 510-km altitude contribute significantly less. We infer that in situ density fluctuations observed on passes over or near Mbarara may be used to indicate the risk that ionospheric radio wave scintillations occur at that site.

中文翻译：

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电离层不规则和闪烁：原位密度观测与陆基 L 波段接收机的直接比较

电离层的不规则性会导致无线电信号闪烁，从而影响卫星通信和导航。闪烁通常使用基于地面的接收器网络进行测量。本研究展示了朗缪尔探测器在 Swarm 卫星上对电离层不规则性的观察结果。它们与安装在 Mbarara 的全球定位系统闪烁网络和决策辅助 (GPS-SCINDA) 接收器记录的幅度闪烁事件进行比较（纬度：$$0.6^{\circ }\hbox {S}$$ 0 . 6 ∘ S , Lon: $$30.8^{\circ }\hbox {E}$$ 30 . 8 ∘ E , Mag. lat: $$10.2^{\circ }\hbox {S}$$ 10 . 2 ∘ S )。该研究涵盖了从 2014 年到 2018 年这两个数据集都可用的年份。发现当 Swarm 记录电离层不规则性时，地面振幅闪烁会增强。与 Swarm B 相比，Swarm A 和 C 在较低高度运行的匹配观测数量更多。 然而，一些反例，即原位电子密度波动与任何观察到的 L 波段振幅闪烁无关，反之亦然，也被发现。因此，观察到的不规则结构和闪烁之间的不匹配可能会在几分钟内和几十公里的距离内发生。使用众所周知的弱散射相位屏模型从电子密度数据估计由S 4 指数表征的振幅闪烁强度。Swarm B 的衍生振幅闪烁平均低于 A 和 C，并且与观察到的范围不符。高度约 450 公里处的不规则对 L 波段闪烁的贡献很大，而约 510 公里高度处的不规则贡献明显较小。我们推断，在 Mbarara 上空或附近观察到的原位密度波动可用于表明该地点发生电离层无线电波闪烁的风险。