Locally adapted NeQuick 2 model performance in European middle latitude ionosphere under different solar, geomagnetic and seasonal conditions

Vuković, Josip; Kos, Tomislav

doi:10.1016/j.asr.2017.05.007

Cited by 6 publications

(5 citation statements)

References 8 publications

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“…As GNSS-derived ionospheric data are captured by a limited number of GNSS receivers, in the areas between the received signals' paths, the state of ionosphere needs to be defined. It can be executed either by normalizing the values of measured ionospheric errors and interpolating in the areas between, or by driving an ionospheric model with such locally available data [55]. In this research, we used a single-layer model of ionosphere, located at a height of 350 km, where the ionization level (which affects the signal propagation) is the highest [56].…”

Section: Type Of Propagationmentioning

confidence: 99%

A Study of Tropospheric and Ionospheric Propagation Conditions during Differential Interferometric SAR Measurements Applied on Zagreb 22 March 2020 Earthquake

2023

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The differential interferometric synthetic aperture radar (DInSAR) method is based on phase variation between the complex value of pixels of timely separated scenes in interferometric SAR pairs. This phase variation has five components: surface topography, curvature of planet’s surface, terrain displacement, volume scatterers, and atmospheric propagation effects. The terrain displacement is the main product of the DInSAR method, while the last two effects are unpredictable and bring inaccuracy into the terrain displacement measurements. In this work, the propagation conditions in the troposphere and ionosphere were studied during two DInSAR measurements examining the Zagreb 22 March 2020 earthquake, with terrain raising of up to +3 cm at the epicenter. For the troposphere, the vertical profile of the modified refraction index, which incorporates local curvature change with height, was reconstructed using aerological balloon probing data. Ionospheric conditions were determined based on total electron content (TEC) calculated from the Croatian positioning system (CROPOS) and global navigation satellite system (GNSS) reference stations’ measurements. One of the DInSAR measurements was conducted in unfavorable tropospheric refractive conditions, which resulted in an overall bias of −2 cm. The variability of propagation conditions indicates the need for examining the atmospheric propagation effects when calculating terrain displacements using the DInSAR method. The results of DInSAR indicate slight displacements, comparable with the amplitude of atmospheric variations, and should therefore be approached with caution.

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Section: Type Of Propagationmentioning

confidence: 99%

A Study of Tropospheric and Ionospheric Propagation Conditions during Differential Interferometric SAR Measurements Applied on Zagreb 22 March 2020 Earthquake

2023

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“…The timing and magnitude of ionospheric disturbances caused by geomagnetic storms are complex, and the ionosphere can have different variability characteristics in different latitudes, which in turn can have a large impact on the performance of GNSS ionospheric delay correction models (D'Angelo et al, 2018;Nava et al, 2016). Therefore, a large number of scholars have evaluated the performance of ionospheric delay correction models for geomagnetic storm disturbance periods, and Vukovi and Kos (2017) analyzed the accuracy of the NeQuick 2 model at European mid-latitudes under different ionospheric activity conditions during the period 2011 to 2015; Jiang et al (2018) analyzed the ionospheric model performance of four ionospheric models for the entire polar region for the polar diurnal, Antarctic ice cap and Arctic Ocean, Weddell Sea anomaly, and ionospheric storms; Liu et al (2019) chose GPS-derived absolute total electron contents (TECs), differences of slant total electron content (dSTEC) observed by independent ground reference stations, Jason-2 derived TECs and absolute TECs calculated from the GIM as references to analyze the performance of different 3D ionospheric models, namely NeQuick2, re-estimated of NeQuickG and IRI-2016, at different levels of geomagnetic activity on a global scale; Liu et al (2018) evaluated the overall performance of GIM at different levels of geomagnetic activity and at different latitudes during 2015-2017 and compared it with the high-quality IGS final TEC; Li et al (2022) analyzed the static standard point positioning accuracy of GPS and BDS based on the broadcast ionospheric model, and then investigated the impact of strong geomagnetic storms occurring in 2021 on the positioning accuracy. Many of these studies have shown that the ionospheric delay correction model performance degrades to different degrees during geomagnetic storms.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of Ionospheric Delay Correction Model Performance During Geomagnetic Storms

Liu,

Song,

Cheng

et al. 2024

Radio Science

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Ionospheric delay, as one of the largest error sources in radio propagation, can only be corrected for this error using the ionospheric delay correction model for Global Navigation Satellite System (GNSS) single‐frequency users. In this paper, the 2021 geomagnetic storm event is selected, and based on the measured ionospheric data from the GNSS observatory, the perturbation of the ionosphere by the geomagnetic storm event is analyzed, and it is found that the response of the ionosphere to the geomagnetic storm has obvious differences in the response characteristics and response time in different latitude regions. The performance of the global ionospheric map (GIM), the empirical model, and the broadcast ionospheric model during the geomagnetic storm‐induced ionospheric perturbation is analyzed and the change in the accuracy of each ionospheric model during the geomagnetic storm‐induced ionospheric perturbation is investigated, using the measured electron content of the GNSS as a benchmark. The results show that there is good agreement between the GIM products and the measured electron content during the period of ionospheric calm and the period of ionospheric perturbation. It is worth noting that geomagnetic storms do not necessarily lead to a decrease in the accuracy of ionospheric delay‐correction models, and in some cases, the models that were originally under‐accurate show a tendency to improve their accuracy during the period of perturbation instead. Neither the broadcast ionospheric model nor the electron content of the empirical model output responds to geomagnetic storm‐induced ionospheric perturbations.

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“…For example, Afraimovich et al () found strong N ‐shaped acoustic waves following the 2008 Wenchuan earthquake with a plane waveform. The features of seismo‐ionospheric disturbances including velocities, propagating direction, and amplitude of the ionospheric anomalies triggered by great earthquakes were further studied (Jin et al, ; Vukovic & Kos, ), but the disturbance mode and the coupling between the earthquake and the ionosphere are still not clear. Understanding disturbance characteristics and the coupling process will contribute to a comprehensive knowledge of the procedure and the mechanism of earthquakes, and help human to mitigate the damage.…”

Section: Introductionmentioning

confidence: 99%

Two‐Mode Ionospheric Disturbances Following the 2005 Northern California Offshore Earthquake From GPS Measurements

Jin

2018

JGR Space Physics

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Seismo-ionospheric anomalies have been reported, while its disturbance modes, patterns, and mechanism are very complex for different kinds of earthquakes. The earthquake with M w = 7.2 occurred off the coast of Northern California with strike-slip faulting on 15 June 2005, which may provide a new insight on ionospheric disturbance waves and patterns from dense Global Positioning System (GPS) observations. In this paper, the detailed seismic ionospheric disturbance modes and characteristics are investigated from dense GPS observations following the 2005 Northern California offshore earthquake. Around 10 min after the earthquake, significant ionospheric disturbances are observed by GPS total electron content (TEC). Furthermore, two-mode ionospheric disturbances are clearly found with two speeds, 1.51 and 2.31 km/s. The slow-propagating mode has an amplitude of 0.02-0.04 total electron content unit (TECU), while the fast-propagating mode has an amplitude of 0.1-0.2 TECU. The frequency spectrogram of the slow mode is around 3.7 mHz, while typical frequency of the fast mode is about 5.3 mHz. The fast-propagating mode is close to the speed of the seismic Rayleigh wave, which is the up propagating secondary acoustic wave triggered by the Rayleigh wave. The slow mode ionospheric disturbance is propagating horizontally as the acoustic wave at the ionospheric level, which is caused by the fault rupture in focal regions.

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Locally adapted NeQuick 2 model performance in European middle latitude ionosphere under different solar, geomagnetic and seasonal conditions

Cited by 6 publications

References 8 publications

A Study of Tropospheric and Ionospheric Propagation Conditions during Differential Interferometric SAR Measurements Applied on Zagreb 22 March 2020 Earthquake

A Study of Tropospheric and Ionospheric Propagation Conditions during Differential Interferometric SAR Measurements Applied on Zagreb 22 March 2020 Earthquake

Analysis of Ionospheric Delay Correction Model Performance During Geomagnetic Storms

Two‐Mode Ionospheric Disturbances Following the 2005 Northern California Offshore Earthquake From GPS Measurements

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