scholarly journals Identification of potential precursors for the occurrence of Large-Scale Traveling Ionospheric Disturbances in a case study during September 2017

2020 ◽  
Vol 10 ◽  
pp. 32
Author(s):  
Arthur Amaral Ferreira ◽  
Claudia Borries ◽  
Chao Xiong ◽  
Renato Alves Borges ◽  
Jens Mielich ◽  
...  
Keyword(s):  
Real Time ◽  
Electron Density ◽  
Large Scale ◽  
Rate Of Change ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Auroral Activity

Traveling Ionospheric Disturbances (TIDs) reflect changes in the ionospheric electron density which are caused by atmospheric gravity waves. These changes in the electron density impact the functionality of different applications such as precise navigation and high-frequency geolocation. The Horizon 2020 project TechTIDE establishes a warning system for the occurrence of TIDs with the motivation to mitigate their impact on communication and navigation applications. This requires the identification of appropriate indicators for the generation of TIDs and for this purpose we investigate potential precursors for the TID occurrence. This paper presents a case study of the double main phase geomagnetic storm, starting from the night of 7th September and lasting until the end of 8th September 2017. Detrended Total Electron Content (TEC) derived from Global Navigation Satellite System (GNSS) measurements from more than 880 ground stations in Europe was used to identify the occurrence of different types of large scale traveling ionospheric disturbances (LSTIDs) propagating over the European sector. In this case study, LSTIDs were observed more frequently and with higher amplitude during periods of enhanced auroral activity, as indicated by increased electrojet index (IE) from the International Monitor for Auroral Geomagnetic Effects (IMAGE). Our investigation suggests that Joule heating due to the dissipation of Pedersen currents is the main contributor to the excitation of the observed LSTIDs. We observe that the LSTIDs are excited predominantly after strong ionospheric perturbations at high-latitudes. Ionospheric parameters including TEC gradients, the Along Arc TEC Rate (AATR) index and the Rate Of change of TEC index (ROTI) have been analysed for their suitability to serve as a precursor for LSTID occurrence in mid-latitude Europe, aiming for near real-time indication and warning of LSTID activity. The results of the presented case study suggest that the AATR index and TEC gradients are promising candidates for near real-time indication and warning of the LSTIDs occurrence in mid-latitude Europe since they have a close relation to the source mechanisms of LSTIDs during periods of increased auroral activity.

scholarly journals A case study of the large-scale traveling ionospheric disturbances in the East Asian sector during the 2015 St. Patrick’s Day geomagnetic storm

2019 ◽  
Author(s):  
Jing Liu ◽  
Dong-He Zhang ◽  
Anthea J. Coster ◽  
Shun-Rong Zhang ◽  
Guan-Yi Ma ◽  
...  
Keyword(s):  
Geomagnetic Storm ◽  
Large Scale ◽  
East Asian ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
East Side ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Propagation Parameters ◽  
Perturbation Maps

Abstract. This study gives the first observation of the large-scale traveling ionospheric disturbances (LSTIDs) in the East Asian sector during the 2015 St. Patrick’s Day (March 17, 2015) geomagnetic storm. For the first time, 3 dense networks of GPS receivers in China and Japan are combined together to obtain the 2-dimensional (2D) vertical total electron content (VTEC) perturbation maps in a wider longitudinal range than previous works in this region. Results show that a negative LSTID spanning at least 60° in longitude (80° E–140° E) occurs and propagating from high to lower latitudes around 09:40–11:20 UT. It is followed by a positive LSTID which shows a tendency of dissipation starting from the East side. The manifestation of the 2D VTEC perturbation maps is in good agreement with the recordings from 2 high-frequency Doppler shift stations and the iso-frequency lines from 8 ionosondes. Then, the propagation parameters of the LSTIDs are estimated by applying least square fitting methods to the distinct structures in the 2D VTEC perturbation plots. In general, the propagation parameters are observably longitudinal dependent. For example, the propagation direction is almost due southward between 105° E–115° E, while it is slightly South by West/East in the West/East side of this region. This feature is probably related to the regional geomagnetic declination. The mean values of the period, trough velocity (Vt), crest velocity (Vc), and wavelength of the wavelike LSTIDs in the studied longitudinal bands are 74.8 ± 1.4 minutes, 578 ± 16 m/s, 617 ± 23 m/s, and 2691 ± 80 km, respectively. Finally, using the VTEC map data from the Madrigal database of the MIT Haystack Observatory, the characteristics of the ionospheric disturbances over the European sector (30° N–70° N, 10° E–20° E) are also studied. The results are very different from those in the East Asian sector in parameters like the occurrence time, oscillation period, and propagation velocities.

scholarly journals Impact of medium-scale traveling ionospheric disturbances on network real-time kinematic services: CATNET study case

2020 ◽  
Vol 10 ◽  
pp. 29
Author(s):  
Cristhian Camilo Timoté ◽  
José Miguel Juan ◽  
Jaume Sanz ◽  
Guillermo González-Casado ◽  
Adrià Rovira-García ◽  
...  
Keyword(s):  
Real Time ◽  
Statistical Tests ◽  
Integer Ambiguity ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Data Set ◽  
Total Electron ◽  
Medium Scale ◽  
Traveling Ionospheric Disturbances ◽  
Position Errors

Medium-scale traveling ionospheric disturbances (MSTIDs) are fluctuations in the plasma density that propagate through the upper layer of the atmosphere at velocities of approximately 100 m/s and periods reaching some tens of minutes. Due to their wavelengths, MSTIDs can degrade the performance of differential positioning techniques, such as real-time kinematics (RTK) or network-RTK (NRTK). This paper defines a novel methodology as a tool for relating the errors in NRTK positioning based on an MSTIDs indicator using the second difference in time of the slant total electron content (STEC). The proposed methodology performs integer ambiguity resolution (IAR) on the undifferenced measurements instead of using double-differenced carrier-phase measurements, as it is usual in RTK and NRTK. Statistical tests are applied to evaluate the degradation in the position errors caused by the impacts of MSTIDs on RTK and NRTK positioning over a data set spanning one year gathered from the CATNET network; a dual-frequency network of fixed permanent GNSS receivers located at the mid-latitudes of northeastern Spain. With the development of the proposed methodology for measuring the position degradation, another results of the present research are the establishment of thresholds for the proposed MSTIDs index, which can be used to monitor the positioning solution and to warn users when the measurements are affected by MSTIDs events, relating the position error to MSTIDs that affect not only the user receivers but also of the reference receivers within the network.

scholarly journals Simultaneous observations of large-scale traveling ionospheric disturbances on the nightside and dayside middle latitude

2012 ◽  
Vol 30 (12) ◽  
pp. 1709-1717 ◽  
Author(s):  
H. T. Cai ◽  
F. Yin ◽  
S. Y. Ma ◽  
J. S. Xu ◽  
Y. W. Liu
Keyword(s):  
North American ◽  
Large Scale ◽  
Source Region ◽  
Phase Speed ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Gps Receiver ◽  
Atmospheric Gravity Wave ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances

Abstract. In this paper, we present further observational evidence for the transpolar propagation of large-scale traveling ionospheric disturbances (LSTIDs) from their nightside source region to the dayside reported by Cai et al. (2011). Slant total electron content (STEC) observed by longitudinally aligned GPS receiver chains in North American and European sectors was analyzed to demonstrate presences of LSTIDs at both nightside and dayside mid-latitude. Signatures of TID were inferred from phase difference in time series of STEC perturbations (TECP) derived from measurements of ground-based GPS receivers, which are separated by hundreds of kilometers longitudinally. Periods of the daytime and nighttime ionospheric disturbances were estimated to be around 128 min, being in good agreement with that of the transpolar AGW (atmospheric gravity wave) recorded by EISCAT (European Incoherent Scatter Scientific Association)/ESR (EISCAT Svalbard Radar) radars. On the dayside, the LSTID moved equatorward with an average phase speed of ~440 m s−1. In North American sector, however, southward speed of the nighttime LSTID was much slower, being around 160 m s−1. We suggest that the observed daytime and nighttime mid-latitude LSTIDs are likely to have the same source region, being located somewhere at nighttime auroral latitude. Having been launched on the nightside, the waves propagate simultaneously equatorward and poleward. The equatorward-moving waves are recorded by GPS receiver chain in North American sector. The poleward-moving waves, however, cross the polar cap from nightside to dayside and then are detected consecutively at high and mid-latitudes by EISCAT/ESR radars and GPS receiver chains, respectively.

scholarly journals Global propagation features of large-scale traveling ionospheric disturbances during the magnetic storm of 7~10 November 2004

2012 ◽  
Vol 30 (4) ◽  
pp. 683-694 ◽  
Author(s):  
Q. Song ◽  
F. Ding ◽  
W. Wan ◽  
B. Ning ◽  
L. Liu
Keyword(s):  
North America ◽  
Phase Velocity ◽  
East Asia ◽  
Magnetic Storm ◽  
Large Scale ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Damping Rate

Abstract. Larger-scale traveling ionospheric disturbances (LSTIDs) were studied using the total electron content (TEC) data observed from global GPS network in the regions of North America, Europe, and East Asia during the magnetic storm of 7~10 November 2004. 4 LSTID events were detected in North America, 4 in Europe, and 3 in East Asia. The parameters of the 11 LSTID events, such as the propagation azimuth (the angle with respect to north, taking clockwise as positive), horizontal phase velocity and damping rate were determined. Our results showed two new propagation features of the LSTIDs. One was the latitudinal dependence of the LSTIDs' propagation azimuths. The LSTIDs tended to deflect more to west from south as they propagated to lower latitudes, which indicated that the Coriolis force was one of the main causes of the LSTIDs' southwestward deviation. The other was the different mean horizontal phase velocities of LSTIDs among different regions. The mean horizontal phase velocity of LSTIDs was 422 ± 36 m s−1 in North America, 381 ± 69 m s−1 in Europe, and 527 ± 21 m s−1 in East Asia, respectively. The results also indicated that the amplitudes of LSTIDs decreased during their propagation for every event, and the daytime damping rates were more than 1 time larger than the nighttime ones due to different ion drag between daytime and nighttime. The source regions of the LSTIDs were likely to be located between geomagnetic latitudes of 68° N and 62° N in North America, and between 65° N and 57° N in Europe, according to the variation of magnetic H component observed in these two regions.

scholarly journals Direct Connection Between Auroral Oval Streamers/Flow Channels and Equatorward Traveling Ionospheric Disturbances

2021 ◽  
Vol 8 ◽  
Author(s):  
Larry R. Lyons ◽  
Yukitoshi Nishimura ◽  
Shunrong Zhang ◽  
Anthea Coster ◽  
Jiang Liu ◽  
...  
Keyword(s):  
Large Scale ◽  
Auroral Oval ◽  
Electron Precipitation ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Direct Connection ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Flow Channels ◽  
Ground Magnetic

We use simultaneous auroral imaging, radar flows, and total electron content (TEC) measurements over Alaska to examine whether there is a direct connection of large-scale traveling ionospheric disturbances (LSTIDs) to auroral streamers and associated flow channels having significant ground magnetic decreases. Observations from seven nights with clearly observable flow channels and/or auroral streamers were selected for analysis. Auroral observations allow identification of streamers, and TEC observations detect ionization enhancements associated with streamer electron precipitation. Radar observations allow direct detection of flow channels. The TEC observations show direct connection of streamers to TIDs propagating equatorward from the equatorward boundary of the auroral oval. The TIDs are also distinguished from the streamers to which they connect by their wave-like TEC fluctuations moving more slowly equatorward than the TEC enhancements from streamer electron precipitation. TIDs previously observed propagating equatorward from the auroral oval have been identified as LSTIDs. Thus, the TIDs here are likely LSTIDs, but we lack sufficient TEC coverage necessary to demonstrate that they are indeed large scale. Furthermore, each of our events shows TID’s connection to groups of a few streamers and flow channels over a period in the order of 15 min and a longitude range of ∼15–20°, and not to single streamers. (Groups of streamers are common during substorms. However, it is not currently known if streamers and associated flow channels typically occur in such groups.) We also find evidence that a flow channel must lead to a sufficiently large ionospheric current for it to lead to a detectable LSTID, with a few tens of nT ground magnetic field decreases not being sufficient.

Traveling Ionospheric Disturbances Characteristics during the 2018 Typhoon Maria from GPS Observations

2020 ◽  
Vol 12 (4) ◽  
pp. 746 ◽  
Author(s):  
Yiduo Wen ◽  
Shuanggen Jin
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Ionospheric Disturbance ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Dual Frequency ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Gps Observations

Typhoons often occur and may cause huge loss of life and damage of infrastructures, but they are still difficult to precisely monitor and predict by traditional in-situ measurements. Nowadays, ionospheric disturbances at a large-scale following typhoons can be monitored using ground-based dual-frequency Global Positioning System (GPS) observations. In this paper the responses of ionospheric total electron content (TEC) to Typhoon Maria on 10 July 2018 are studied by using about 150 stations of the GPS network in Taiwan. The results show that two significant ionospheric disturbances on the southwest side of the typhoon eye were found between 10:00 and 12:00 UTC. This was the stage of severe typhoon and the ionospheric disturbances propagated at speeds of 118.09 and 186.17 m/s, respectively. Both traveling ionospheric disturbances reached up to 0.2 TECU and the amplitudes were slightly different. The change in the filtered TEC time series during the typhoon was further analyzed with the azimuth. It can be seen that the TEC disturbance anomalies were primarily concentrated in a range of between −0.2 and 0.2 TECU and mainly located at 135–300° in the azimuth, namely the southwest side of the typhoon eye. The corresponding frequency spectrum of the two TEC time series was about 1.6 mHz, which is consistent with the frequency of gravity waves. Therefore, the upward propagating gravity wave was the main cause of the traveling ionospheric disturbance during Typhoon Maria.

scholarly journals A case study of the large-scale traveling ionospheric disturbances in the eastern Asian sector during the 2015 St. Patrick's Day geomagnetic storm

2019 ◽  
Vol 37 (4) ◽  
pp. 673-687 ◽  
Author(s):  
Jing Liu ◽  
Dong-He Zhang ◽  
Anthea J. Coster ◽  
Shun-Rong Zhang ◽  
Guan-Yi Ma ◽  
...  
Keyword(s):  
Geomagnetic Storm ◽  
Large Scale ◽  
Least Square ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Traveling Ionospheric Disturbances ◽  
Propagation Parameters ◽  
Perturbation Maps

Abstract. This study presents a comprehensive observation of the large-scale traveling ionospheric disturbances (LSTIDs) in the eastern Asian sector during the 2015 St. Patrick's Day (17 March 2015) geomagnetic storm. For the first time, three dense networks of GPS receivers in China and Japan are combined together to obtain the two-dimensional (2-D) vertical total electron content (VTEC) perturbation maps in a wider longitudinal range than previous studies in this region. Results show that an LSTID spanning at least 60∘ in longitude (80–140∘ E) occurs as a result of possible atmospheric gravity waves (AGWs) propagating from high to lower latitudes at around 09:40–11:40 UT (universal time), and the crest of this LSTID shows a tendency of dissipation starting from the eastern side. The manifestation of the 2-D VTEC perturbation maps is in good agreement with the recordings from two high-frequency Doppler sounders and the iso-frequency lines from eight ionosondes. Then, the propagation parameters of the LSTIDs are estimated by applying least-square fitting methods to the distinct structures in the 2-D VTEC perturbation plots. In general, the propagation parameters are observably longitudinally dependent. For example, the propagation direction is almost due southward between 105 and 115∘ E, while it is slightly southwest and southeast in the western and eastern sides of this region. This feature is probably related to the regional geomagnetic declination. The mean values of the period, trough velocity (Vt), crest velocity (Vc), and wavelength of the LSTIDs in the studied longitudinal bands are 74.8±1.4 min, 578±16 m s−1, 617±23 m s−1, and 2691±80 km, respectively. Finally, using the VTEC map data from the Madrigal database of the MIT Haystack Observatory, the characteristics of the ionospheric disturbances over the European sector (30–70∘ N, 10–20∘ E) are also studied. The results are very different from those in the eastern Asian sector in parameters like the occurrence time, oscillation period, and propagation velocities.

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