Polar Electron Content From GPS Data‐Based Global Ionospheric Maps: Assessment, Case Studies, and Climatology

The purpose of the present study is to investigate simultaneously pre-earthquake ionospheric and atmospheric disturbances by the application of different methodologies, with the ultimate aim to detect their possible link with the impending seismic event. Three large earthquakes in Mexico are selected (8.2 Mw, 7.1 Mw and 6.6 Mw during 8 and 19 September 2017 and 21 January 2016 respectively), while ionospheric variations during the entire year 2017 prior to 37 earthquakes are also examined. In particular, Total Electron Content (TEC) retrieved from Global Navigation Satellite System (GNSS) networks and Atmospheric Chemical Potential (ACP) variations extracted from an atmospheric model are analyzed by performing statistical and spectral analysis on TEC measurements with the aid of Global Ionospheric Maps (GIMs), Ionospheric Precursor Mask (IPM) methodology and time series and regional maps of ACP. It is found that both large and short scale ionospheric anomalies occurring from few hours to a few days prior to the seismic events may be linked to the forthcoming events and most of them are nearly concurrent with atmospheric anomalies happening during the same day. This analysis also highlights that even in low-latitude areas it is possible to discern pre-earthquake ionospheric disturbances possibly linked with the imminent seismic events.

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Functional model modification of precise point positioning considering the time-varying code biases of a receiver

Satellite Navigation ◽

10.1186/s43020-021-00040-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Baocheng Zhang ◽

Chuanbao Zhao ◽

Robert Odolinski ◽

Teng Liu

Keyword(s):

Precise Point Positioning ◽

Functional Model ◽

Geodetic Network ◽

Temporal Variations ◽

Gps Data ◽

Electron Content ◽

Time Varying ◽

Dual Frequency ◽

Total Electron ◽

Point Positioning

AbstractPrecise Point Positioning (PPP), initially developed for the analysis of the Global Positing System (GPS) data from a large geodetic network, gradually becomes an effective tool for positioning, timing, remote sensing of atmospheric water vapor, and monitoring of Earth’s ionospheric Total Electron Content (TEC). The previous studies implicitly assumed that the receiver code biases stay constant over time in formulating the functional model of PPP. In this contribution, it is shown this assumption is not always valid and can lead to the degradation of PPP performance, especially for Slant TEC (STEC) retrieval and timing. For this reason, the PPP functional model is modified by taking into account the time-varying receiver code biases of the two frequencies. It is different from the Modified Carrier-to-Code Leveling (MCCL) method which can only obtain the variations of Receiver Differential Code Biases (RDCBs), i.e., the difference between the two frequencies’ code biases. In the Modified PPP (MPPP) model, the temporal variations of the receiver code biases become estimable and their adverse impacts on PPP parameters, such as ambiguity parameters, receiver clock offsets, and ionospheric delays, are mitigated. This is confirmed by undertaking numerical tests based on the real dual-frequency GPS data from a set of global continuously operating reference stations. The results imply that the variations of receiver code biases exhibit a correlation with the ambient temperature. With the modified functional model, an improvement by 42% to 96% is achieved in the Differences of STEC (DSTEC) compared to the original PPP model with regard to the reference values of those derived from the Geometry-Free (GF) carrier phase observations. The medium and long term (1 × 104 to 1.5 × 104 s) frequency stability of receiver clocks are also significantly improved.

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Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

Annales Geophysicae ◽

10.5194/angeo-26-893-2008 ◽

2008 ◽

Vol 26 (4) ◽

pp. 893-903 ◽

Cited By ~ 27

Author(s):

◽

Keyword(s):

Total Electron Content ◽

Geomagnetic Activity ◽

Electron Content ◽

Low Latitude ◽

Total Electron ◽

Defense Meteorological Satellite Program ◽

Low Latitudes ◽

Global Ionospheric Maps ◽

Geomagnetic Activities

Abstract. Sometimes the ionospheric total electron content (TEC) is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS) observations in the Asia/Australia sector as well as global ionospheric maps (GIMs) produced by Jet Propulsion Laboratory (JPL). Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA) crests, which are consistent with those low-latitude events presented by Liu et al. (2008). During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP) spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event). Further investigation is warrented to identify/separate contributions from possible sources.

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Global Variations of Ionospheric Total Electron Content (TEC) Derived from GPS Global Ionospheric Maps

Momona Ethiopian Journal of Science ◽

10.4314/mejs.v9i2.2 ◽

2017 ◽

Vol 9 (2) ◽

pp. 141

Author(s):

Hintsa Gebreselasse ◽

Gebregiorgis Abraha

Keyword(s):

Total Electron Content ◽

Electron Content ◽

Total Electron ◽

Ionospheric Total Electron Content ◽

Global Ionospheric Maps

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EFEK CME HALO PENUH PADA IONOSFER LINTANG RENDAH DARI DATA GPS BAKO DI CIBINONG [EFFECT OF FULL HALO CME ON LOW LATITUDE IONOSPHERE FROM BAKO GPS DATA IN CIBINONG]

Jurnal Sains Dirgantara ◽

10.30536/j.jsd.2017.v15.a2735 ◽

2018 ◽

Vol 15 (1) ◽

pp. 51

Author(s):

Fakhrizal Muttaqien ◽

Buldan Muslim

Keyword(s):

Total Electron Content ◽

Geomagnetic Storm ◽

Geomagnetic Disturbance ◽

Main Phase ◽

Gps Data ◽

Electron Content ◽

Ionospheric Storm ◽

Total Electron ◽

Dst Index ◽

Software Analysis

A full halo coronal mass ejections (CMEs) are most energetic solar events that eject huge amount of mass and magnetic fields into heliosphere with 360o angular angle. The full halo CME effect on the ionosphere can be determined from the ionospheric total electron content (TEC) derived from GPS data. GPS data from BAKO station in Cibinong, satellite orbital data (brcd files) and intrumental bias data (DCB files) have been used to obtain TEC using GOPI software. Analysis of the full halo CME data, Dst index, and TEC during October 2003 and February 2014 showed that the full halo CME could cause ionospheric disturbances called ionospheric storms. Magnitude and time delay of the ionospheric storms depended on the full halo CME speed. For the high-speed full halo CME, the negative ionospheric storm generally occured during recovery phase of the geomagnetic storm. When the initial phase of geomagnetic disturbance with increasing Dst index more than +30 nT, the ionospheric storm occured during main phase of geomagnetic disturbance although the main phase of geomagnetic disturbance did not reach geomagnetic storm condition. ABSTRAKCoronal mass ejection (CME) halo penuh merupakan peristiwa matahari berenergi tinggi, yang menyemburkan massa dan medan magnet ke heliosfer dengan sudut angular sebesar 360º. Efek CME halo penuh pada ionosfer dapat diketahui dari Total Electron Content (TEC). Data GPS BAKO di Cibinong, data orbit satelit (file brcd) dan data bias instrumental (file DCB) dapat digunakan untuk penentuan TEC menggunakan software GOPI. Analisis data CME halo penuh, indeks Dst, dan TEC selama bulan Oktober 2003 dan Februari 2014 menunjukkan bahwa CME halo penuh dapat menimbulkan gangguan ionosfer yang disebut badai ionosfer. Besar dan selang waktu badai ionosfer setelah terjadinya CME, tergantung pada kelajuan CME halo penuh. Untuk CME halo penuh berkelajuan tinggi, badai ionosfer negatif umumnya terjadi pada fase pemulihan badai geomagnet. Jika fase awal gangguan geomagnet diawali dengan peningkatan indeks Dst melebihi +30 nT, maka badai ionosfer dapat terjadi pada fase utama gangguan geomagnet walau gangguan geomagnet setelah fase awal tidak mencapai kondisi badai geomagnet.

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Localized TEC enhancements in the Southern Hemisphere

10.5194/angeo-2019-124 ◽

2019 ◽

Author(s):

Ilya K. Edemskiy

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Southern Hemisphere ◽

Occurrence Rate ◽

Continuous Series ◽

Electron Content ◽

Field Orientation ◽

Total Electron ◽

Magnetic Field Orientation ◽

Global Ionospheric Maps

Abstract. The paper is dedicated to investigation of localized TEC (total electron content) enhancements (LTEs), particularly of LTE series, detected in the Southern Hemisphere using global ionospheric maps for different solar activity years (2014, 2015, 2018). It is shown that LTE intensity varies in dependence on solar flux and does not directly depend on interplanetary magnetic field orientation. The enhancements occur in a subsolar region and could be observed during a continuous series of days. The highest LTE occurrence rate is observed during period of local winter (April-September) for all analyzed years. The longest observed LTE series was detected during 2014 and lasted 80 days or 120 days if we exclude 2 daily gaps.

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On Global Ionospheric Maps based winter-time GPS ionospheric delay with reference to the Klobuchar model

Pomorstvo ◽

10.31217/p.33.2.11 ◽

2019 ◽

Vol 33 (2) ◽

pp. 210-221

Author(s):

David Brčić ◽

Renato Filjar ◽

Serdjo Kos ◽

Marko Valčić

Keyword(s):

Ionospheric Delay ◽

Single Frequency ◽

Electron Content ◽

Ground Truth Data ◽

Local Pattern ◽

Satellite Positioning ◽

Klobuchar Model ◽

Global Ionospheric Maps ◽

Winter Time ◽

Delay Correction

Modelling of the ionospheric Total Electron Content (TEC) represents a challenging and demanding task in Global Navigation Satellite Systems (GNSS) positioning performance. In terms of satellite Positioning, Navigation and Timing (PNT), TEC represents a significant cause of the satellite signal ionospheric delay. There are several approaches to TEC estimation. The Standard (Klobuchar) ionospheric delay correction model is the most common model for Global Positioning System (GPS) single-frequency (L1) receivers. The development of International GNSS Service (IGS) Global Ionospheric Maps (GIM) has enabled the insight into global TEC dynamics. GIM analyses in the Northern Adriatic area have shown that, under specific conditions, local ionospheric delay patterns differ from the one defined in the Klobuchar model. This has been the motivation for the presented research, with the aim to develop a rudimentary model of the TEC estimation, with emphasis on areas where ground truth data are not available. The local pattern of the ionospheric delay has been modelled with wave functions based on the similarity of waveforms, considering diurnal differences in TEC behavior from defined TEC patterns. The model represents a spatiotemporal winter-time ionospheric delay correction with the Klobuchar model as a basis. The evaluation results have shown accurate approximation of the local pattern of the ionospheric delay. The model was verified in the same seasonal period in 2007, revealing it successfulness under pre-defined conditions. The presented approach represents a basis for the further work on the local ionospheric delay modelling, considering local ionospheric and space weather conditions, thus improving the satellite positioning performance for single-frequency GNSS receivers.

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Analysis of Total Electron Content (TEC) Near Real Time Using Dual Frequency GPS Data (Study Case: Surabaya)

E3S Web of Conferences ◽

10.1051/e3sconf/20199405005 ◽

2019 ◽

Vol 94 ◽

pp. 05005 ◽

Cited By ~ 2

Author(s):

Mokhamad Nur Cahyadi ◽

Almas Nandityo Rahadyan ◽

Buldan Muslim

Keyword(s):

Total Electron Content ◽

Electromagnetic Waves ◽

Signal Propagation ◽

Gps Data ◽

Electron Content ◽

Dual Frequency ◽

Additional Time ◽

Ionospheric Correction ◽

Total Electron ◽

A Value

Ionosphere is part of the atmospheric layer located between 50 to 1000 km above the earth's surface which consists of electrons that can influence the propagation of electromagnetic waves in the form of additional time in signal propagation, this depends on Total Electron Content (TEC) in the ionosphere and frequency GPS signal. In high positioning precision with GPS, the effect of the ionosphere must be estimated so that ionospheric correction can be determined to eliminate the influence of the ionosphere on GPS observation. Determination of ionospheric correction can be done by calculating the TEC value using dual frequency GPS data from reference stations or models. In making the TEC model, a polynomial function is used for certain hours. The processing results show that the maximum TEC value occurs at noon at 2:00 p.m. WIB for February 13, 2018 with a value of 35,510 TECU and the minimum TEC value occurs in the morning at 05.00 WIB for February 7, 2018 with a value of 2,138 TECU. The TEC model spatially shows the red color in the area of Surabaya and its surroundings for the highest TEC values during the day around 13.00 WIB to 16.00 WIB.

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