Evaluation the quality of FORMOSAT-7/COSMIC-2 Observation Data and its application for ionospheric monitoring during the extreme space weather

2021 ◽  
Author(s):  
Ang Li
Keyword(s):  
Space Weather ◽  
The United States ◽  
Electron Content ◽  
Observation Data ◽  
Total Electron ◽  
Orbital Inclination ◽  
High Vertical Resolution ◽  
Global Coverage ◽  
The Difference ◽  
New Generation

<p>Owing to the advantages of high vertical resolution, global coverage, high precision, and all-weather operation, GNSS occultation has been widely used for ionospheric weather monitoring and meteorological forecast. Aiming to obtain the meteorological, climatic, and ionospheric information, FORMOSAT-7/COSMIC-2, the successor constellation of COSMIC-1, is jointly launched by the United States and Taiwan on June 25, 2019. As a new generation occultation constellation, COSMIC-2 consists of six low-latitude satellites with an orbital inclination of 24 degrees and an altitude of 520km. In contrast, COSMIC1 consists of the high-latitude satellites with an orbital inclination of 72 degrees and an orbital altitude of 720km. These differences in constellation structure, orbital altitude, and inclination inevitably lead to the difference in observation quality.</p><p> </p><p>Firstly, in this contribution, the qualities of satellite-based GNSS observations from COSMIC-2 and COSMIC-1 are both analyzed and compared. The result shows that the satellite-based observation data of COSMIC-2 are improved significantly compared with COSMIC-1. The multipath effect reduced by more than 40%, and the probability of cycle slip decreased by three times. Then the occultation observations of the two constellations are also analyzed. Next, using the observations of COSMIC-2 satellites in 2020, an ionospheric total electron content (TEC) model was established. Finally, the TEC model was adopted for investigating the ionospheric disturbances under extreme space weather in 2020.</p><p> </p><p><strong>Keywords</strong>: COSMIC-2; Ionospheric TEC Model; Extreme Space Weather</p>

scholarly journals Accuracy Analysis of International Reference Ionosphere 2016 and NeQuick2 in the Antarctic

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1551
Author(s):  
Zihuai Guo ◽  
Yibin Yao ◽  
Jian Kong ◽  
Gang Chen ◽  
Chen Zhou ◽  
...  
Keyword(s):  
Solar Radiation ◽  
International Reference Ionosphere ◽  
Electron Content ◽  
Observation Data ◽  
Dual Frequency ◽  
Total Electron ◽  
International Reference ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Frequency Observation

Global navigation satellite system (GNSS) can provide dual-frequency observation data, which can be used to effectively calculate total electron content (TEC). Numerical studies have utilized GNSS-derived TEC to evaluate the accuracy of ionospheric empirical models, such as the International Reference Ionosphere model (IRI) and the NeQuick model. However, most studies have evaluated vertical TEC rather than slant TEC (STEC), which resulted in the introduction of projection error. Furthermore, since there are few GNSS observation stations available in the Antarctic region and most are concentrated in the Antarctic continent edge, it is difficult to evaluate modeling accuracy within the entire Antarctic range. Considering these problems, in this study, GNSS STEC was calculated using dual-frequency observation data from stations that almost covered the Antarctic continent. By comparison with GNSS STEC, the accuracy of IRI-2016 and NeQuick2 at different latitudes and different solar radiation was evaluated during 2016–2017. The numerical results showed the following. (1) Both IRI-2016 and NeQuick2 underestimated the STEC. Since IRI-2016 utilizes new models to represent the F2-peak height (hmF2) directly, the IRI-2016 STEC is closer to GNSS STEC than NeQuick2. This conclusion was also confirmed by the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) occultation data. (2) The differences in STEC of the two models are both normally distributed, and the NeQuick2 STEC is systematically biased as solar radiation increases. (3) The root mean square error (RMSE) of the IRI-2016 STEC is smaller than that of the NeQuick2 model, and the RMSE of the two modeling STEC increases with solar radiation intensity. Since IRI-2016 relies on new hmF2 models, it is more stable than NeQuick2.

Could the Beirut Explosion perturb the Ionosphere? Pre-results Using TEC-GNSS observations.

2021 ◽  
Author(s):  
Mohamed Freeshah ◽  
Xiaohong Zhang ◽  
Erman Şentürk ◽  
Xiaodong Ren ◽  
Muhammad Arqim Adil ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Space Weather ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Free Electrons ◽  
Total Electron ◽  
Satellite Systems ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Global Navigation Satellite

<p>Natural hazards such as shallow earthquakes and volcanic explosions are known to generate acoustic and gravity waves at infrasonic velocity to propagate in the atmosphere layers. These waves could induce the layers of the ionosphere by change the electron density based on the neutral particles and free electrons coupling. Recently, some studies have dealt with some manmade hazards such as buried explosions and underground nuclear explosions which could cause a trigger to the ionosphere. The Global Navigation Satellite Systems (GNSS) provide a good way to measure ionospheric total electron content (TEC) through the line of sight (LOS) from satellite to receiver. The carrier-to-code leveling (CCL) technique is carried out for each continuous arc where CCL eliminates potential ambiguity influence and it degrades the pseudo-range noise. Meanwhile, the CCL retains high precision in the carrier-phase. In this study, we focus on the Beirut Explosion on August 4, 2020, to check slant TEC (STEC) variations that may be associated with the blast of Beirut Port. The TECs were analyzed through the Morlet wavelet to check the possible ionospheric response to the blast. An acoustic‐gravity wave could be generated by the event which could disturb the ionosphere through coupling between solid earth-atmosphere-ionosphere during the explosion. To verify TEC disturbances are not associated with space weather, disturbance storm-time (Dst), and Kp indices were investigated before, during, and after the explosion. The steady-state of space weather before and during the event indicated that the observed variations of TEC sequences were caused by the ammonium nitrate explosion. There was a large initial explosion, followed by a series of smaller blasts, about ~30 seconds, a colossal explosion has happened, a supersonic blast wave radiating through Beirut City. As a result of the chemistry behind ammonium nitrate’s explosive, a mushroom cloud was sent into the air. We suggest that these different explosions in strength and time could be the reason for different time arrival of the detected ionospheric disturbances over GNSS ground-based stations.</p>

scholarly journals Data Assimilation for Ionospheric Space-Weather Forecasting in the Presence of Model Bias

2021 ◽  
Vol 7 ◽  
Author(s):  
Juan Durazo ◽  
Eric J. Kostelich ◽  
Alex Mahalov
Keyword(s):  
Data Assimilation ◽  
Space Weather ◽  
Bias Correction ◽  
Geomagnetic Storms ◽  
Circulation Model ◽  
Storm Event ◽  
Electron Content ◽  
Systematic Bias ◽  
Total Electron ◽  
Mean Square Errors

The dynamics of many models of physical systems depend on the choices of key parameters. This paper describes the results of some observing system simulation experiments using a first-principles model of the Earth’s ionosphere, the Thermosphere Ionosphere Electrodynamics Global Circulation Model (TIEGCM), which is driven by parameters that describe solar activity, geomagnetic conditions, and the state of the thermosphere. Of particular interest is the response of the ionosphere (and predictions of space weather generally) during geomagnetic storms. Errors in the overall specification of driving parameters for the TIEGCM (and similar dynamical models) may be especially large during geomagnetic storms, because they represent significant perturbations away from more typical interactions of the earth-sun system. Such errors can induce systematic biases in model predictions of the ionospheric state and pose difficulties for data assimilation methods, which attempt to infer the model state vector from a collection of sparse and/or noisy measurements. Typical data assimilation schemes assume that the model produces an unbiased estimate of the truth. This paper tests one potential approach to handle the case where there is some systematic bias in the model outputs. Our focus is on the TIEGCM when it is driven with solar and magnetospheric inputs that are systematically misspecified. We report results from observing system experiments in which synthetic electron density vertical profiles are generated at locations representative of the operational FormoSat-3/COSMIC satellite observing platforms during a moderate (G2, Kp = 6) geomagnetic storm event on September 26–27, 2011. The synthetic data are assimilated into the TIEGCM using the Local Ensemble Transform Kalman Filter with a state-augmentation approach to estimate a small set of bias-correction factors. Two representative processes for the time evolution of the bias in the TIEGCM are tested: one in which the bias is constant and another in which the bias has an exponential growth and decay phase in response to strong geomagnetic forcing. We show that even simple approximations of the TIEGCM bias can reduce root-mean-square errors in 1-h forecasts of total electron content (a key ionospheric variable) by 20–45%, compared to no bias correction. These results suggest that our approach is computationally efficient and can be further refined to improve short-term predictions (∼1-h) of ionospheric dynamics during geomagnetic storms.

scholarly journals New GGOS JWG3 on Improved understanding of space weather events and their monitoring

2020 ◽  
Author(s):  
Alberto Garcia-Rigo ◽  
Benedikt Soja
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
International Association ◽  
Real Data ◽  
Weather Conditions ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Weather Events ◽  
Space Geodetic Techniques

<p>Multiple space geodetic techniques are capable of measuring effects caused by space weather events. In particular, space weather events can cause ionospheric disturbances correlated with variations in the vertical total electron content (VTEC) or the electron density (Ne) of the ionosphere.</p><p>In this regard and in the context of the new Focus Area on Geodetic Space Weather Research within IAG’s GGOS (International Association of Geodesy; Global Geodetic Observing System), the Joint Working Group 3 on Improved understanding of space weather events and their monitoring by satellite missions has been created as part of IAG Commission 4, Sub-Commission 4.3 to run for the next four years.</p><p>Within JWG3, we expect investigating different approaches to monitor space weather events using the data from different space geodetic techniques and, in particular, combinations thereof. Simulations will be beneficial to identify the contribution of different techniques and prepare for the analysis of real data. Different strategies for the combination of data will also be investigated, in particular, the weighting of estimates from different techniques in order to increase the performance and reliability of the combined estimates. Furthermore, existing algorithms for the detection and prediction of space weather events will be explored and improved to the extent possible. Furthermore, the geodetic measurement of the ionospheric electron density will be complemented by direct observations from the Sun gathered from existing spacecraft, such as SOHO, ACE, SDO, Parker Solar Probe, among others. The combination and joint evaluation of multiple datasets with the measurements of space geodetic observation techniques (e.g. geodetic VLBI) is still a great challenge. In addition, other indications for solar activity - such as the F10.7 index on solar radio flux, SOLERA as EUV proxy or rate of Global Electron Content (dGEC)-, provide additional opportunities for comparisons and validation.</p><p>Through these investigations, we will identify the key parameters useful to improve real-time/prediction of ionospheric/plasmaspheric VTEC, Ne estimates, as well as ionospheric perturbations, in case of extreme solar weather conditions. In general, we will gain a better understanding of space weather events and their effect on Earth’s atmosphere and near-Earth environment.</p>

scholarly journals Analisis Total Electron Content (TEC) Menggunakan Continous Wavelet Transform Sebagai Indikator Prekursor Gempa Bumi Di Wilayah Provinsi Bengkulu

2019 ◽  
Vol 9 (2) ◽  
pp. 27-33
Author(s):  
Laksamana Agung Aprillo ◽  
Hendy Santosa ◽  
Faisal Hadi
Keyword(s):  
Wavelet Transform ◽  
Standard Deviation ◽  
Total Electron Content ◽  
Electromagnetic Waves ◽  
Electron Content ◽  
Observation Data ◽  
Dual Frequency ◽  
Total Electron ◽  
Gps Observation ◽  
Large Earthquakes

ABSTRACT Bengkulu is one of 34 provinces in Indonesia which is a megathrust region. So Bengkulu province is often hit by many large earthquakes with shallow depth. TEC anomaly was analyzed based on three electromagnetic waves radiated by an earthquake. The total electron content (TEC) anomaly is seen through the global positioning system (GPS) dual-frequency radio signal data. The continuous wavelet transform (CWT) method is used to divide the signal analysis into several sections according to the electromagnetic wave frequency range of acoustic (2.5 mHz) -3 mHz), gravity waves (1 mHz-2.8 mHz) and rayleigh waves (5 mHz-33 mHz). GPS observation data for 9 days is calculated using the Standard deviation (2?) method to see trends in data changes. The analysis shows anomalies in the September 12 2007 earthquake (7.9 Mw), the March 5 2010 earthquake (6.3 Mw) and the August 4 2011 earthquake (6.0 Mw). Anomalies are detected 1 to 5 hours before an earthquake occurs. TEC anomalies that occur may be related to the process of preseismic before the earthquake and may be an early sign of an earthquake.Keyword: earthquake, total electron content, continous wavelet transform, standard deviation

Modeling of TEC over the Iberian Peninsula using PCA decomposition and multiple linear regression on space weather parameters

2021 ◽  
Author(s):  
Anna Morozova ◽  
Tatiana Barlyaeva ◽  
Teresa Barata
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Iberian Peninsula ◽  
Space Weather ◽  
Multiple Linear Regression Model ◽  
Principal Component ◽  
Electron Content ◽  
Time Lags ◽  
Total Electron ◽  
Weather Parameters

<p>The total electron content (TEC) over the Iberian Peninsula was modeled using a three-step procedure. At the 1<sup>st</sup> step the TEC series is decomposed using the principal component analysis (PCA) into several daily modes. Then, the amplitudes of those daily modes is fitted by a multiple linear regression model (MRM) using several types of space weather parameters as regressors. Finally, the TEC series is reconstructed using the PCA daily modes and MRM fitted amplitudes.</p><p>The advantage of such approach is that seasonal variations of the TEC daily modes are automatically extracted by PCA. As space weather parameters we considered proxies for the solar UV and XR fluxes, number of the solar flares, parameters of the solar wind and the interplanetary magnetic field, and geomagnetic indices. Different time lags and combinations of the regressors are tested.</p><p>The possibility to use such TEC models for forecasting was tested. Also, a possibility to use neural networks (NN) instead of MRM is studied.</p>

scholarly journals Geomagnetic storm effects on GPS based navigation

2009 ◽  
Vol 27 (5) ◽  
pp. 2101-2110 ◽  
Author(s):  
P. V. S. Rama Rao ◽  
S. Gopi Krishna ◽  
J. Vara Prasad ◽  
S. N. V. S. Prasad ◽  
D. S. V. V. D. Prasad ◽  
...  
Keyword(s):  
Space Weather ◽  
Geomagnetic Storms ◽  
Electron Content ◽  
Navigation Systems ◽  
Dual Frequency ◽  
Storm Activity ◽  
Total Electron ◽  
Gps Receivers ◽  
A Chain ◽  
Phase Slips

Abstract. The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere) comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS) that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena. Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC) measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB) L-band scintillation events, adversely affecting the GPS based navigation.

Low-Earth-Orbit observations for space weather and space climate

2020 ◽  
Author(s):  
Irina Zakharenkova ◽  
Iurii Cherniak ◽  
Sergey Sokolovskiy ◽  
William Schreiner ◽  
Qian Wu ◽  
...  
Keyword(s):  
Electron Density ◽  
Plasma Density ◽  
Space Weather ◽  
Ionospheric Plasma ◽  
Radio Occultation ◽  
Satellite Orbit ◽  
Electron Content ◽  
Gps Measurements ◽  
Total Electron ◽  
Ionospheric Plasma Density

<p>Many of the modern Low-Earth-Orbiting satellites are now equipped with dual-frequency GPS receivers for Radio Occultation (RO) and Precise Orbit Determination (POD). The space-borne GPS measurements can be successfully utilized for ionospheric climatology and space weather monitoring. The combination of GPS measurements, which include RO observations and POD measurements from the upward-looking GPS antenna, provides information about electron density distribution (profile) below the satellite orbit and an integrated Total Electron Content (TEC) above the satellite representing an important data source for electron density climatology above the F2 layer peak on a global scale. We demonstrate the advantages of using space-borne LEO GPS measurements, both RO and upward-looking, for Space Weather activity monitoring including specification of ionospheric plasma density structures at different altitudinal domains of the ionosphere in quiet and disturbed conditions. After the great success of the COSMIC-1 (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission operating since 2006, the six COSMIC-2 satellites were launched into a 24 deg inclination orbit in June 2019. The COSMIC-2 scientific payloads with the advanced Tri-GNSS Radio-Occultation Receiver System provide multiple observation types including multi-GNSS TEC (limb and overhead), RO electron density profiles, amplitude/phase scintillation indices, in-situ ion densities and velocities. The COSMIC-2 advanced instruments allow detection of ionospheric plasma density structures of various scales, and the monitoring of high-rate amplitude and phase scintillations both above and below a satellite orbit. The COSMIC-2 multi-instrumental observations will contribute to a better understanding of the equatorial ionosphere morphology and future forecasting of ionospheric irregularities and radio wave scintillations that harmfully affect satellite-to-Earth communication and navigation systems. We present results of post-event analyses for severe space weather events demonstrating a great potential and contribution of the COSMIC-1/2 missions in combination with the ground-based GNSS receivers and other LEO missions like C/NOFS, DMSP, MetOp, TerraSAR-X, and Swarm for monitoring the space weather effects in the Earth’s ionosphere.</p>

Efficient global ionospheric modeling based on multi-source and massive observation data

2020 ◽  
Author(s):  
Xulei Jin ◽  
Shuli Song ◽  
Wei Li ◽  
Na Cheng
Keyword(s):  
Real Time ◽  
Rapid Development ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Observation Data ◽  
Total Electron ◽  
Ionospheric Modeling ◽  
Virtual Observation ◽  
Data Missing ◽  
Modeling Strategy

<p><strong><span>Abstract</span></strong><span> Ionosphere is an important error source of satellite navigation and a key component of space weather. With the rapid development of multiple Global Navigation Satellite System (GNSS) and other ionospheric research technologies, and the high precision and near real-time requirements for ionospheric products, it is necessary to carry out a research on multi-source data fusion, massive data processing and near-real-time solution of global ionosphere model (GIM); therefore, we modified the traditional ionospheric modeling technology and generate the GIM products (GIM/SHA). In view of the defect of ground-based GNSS data missing in the ocean regions, the method of adding virtual observation stations to the data missing regions in a large range was adopted, which not only enhanced the accuracy of the GIM in the ocean regions, but also avoided the weight determination among different data sources. In terms of near-real-time modeling, the multi-threaded parallel modeling strategy was adopted.</span> <span>Four GNSS (GPS, GLONASS, BEIDOU, Galileo) observation data, eight virtual observation stations and a server with a CPU frequency of 2.1 GHz and 16 threads were utilized. It took less than 30 minutes to construct the GIM by using parallel modeling strategy, which was 10.3 times faster than serial modeling strategy. The accuracy of the GIM/SHA was verified by using the ionospheric products of International GNSS Service (IGS) Ionosphere Associate Analysis Centers (IAACs) in the period of day of year (DOY) 200-365, 2019. Compared with the ionospheric products of CODE, ESA/ESOC, JPL, UPC, EMR, CAS and WHU, the vertical total electron content (VTEC) root mean squares (RMSs) were 1.09 TEC units (TECu), 1.51TECu, 2.32TECu, 1.88TECu, 2.24TECu, 1.25TECu and 1.38TECu, respectively. The result shows that the GIM/SHA have comparable accuracy with IGS ionospheric products. Satellite altimetry data was exploited to verify the accuracy of GIM/SHA in ocean regions, and it can be concluded that the accuracy of the GIM in ocean regions can be significantly reinforced by adding virtual observation stations in ocean regions. Multi-system and multi-frequency differential code bias (DCB) products (DCB/SHA) were simultaneously generated. Compared with IGS DCB products, the satellite DCB RMSs of DCB/SHA were 0.16ns for GPS, 0.08ns for GLONASS, 0.17ns for BEIDOU and 0.14ns for Galileo; the GNSS receiver DCB RMSs of DCB/SHA were 0.69ns for GPS, 1.06ns for GLONASS, 0.75 for BEIDOU and 1.03ns for Galileo. It can be proved that the accuracy of DCB/SHA are comparable to IGS DCB products.</span></p><p><strong><span>Keywords</span></strong><span> Multi-GNSS; GIM; Virtual observation station; Near real-time; VTEC; DCB</span></p>

Hemispheric asymmetry of the ionospheric variation during major sudden stratospheric warming events

2020 ◽  
Author(s):  
Donghe Zhang ◽  
Jing Liu
Keyword(s):  
Hemispheric Asymmetry ◽  
Relative Strength ◽  
Magnetic Equator ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Total Electron ◽  
The North ◽  
Latitudinal Variations ◽  
The Difference

<p>The hemispheric asymmetry of the ionospheric variation in the American sector (45°N~45°S, MLAT; 80°~60°W) is studied with total electron content (TEC) data during major sudden stratospheric warming events. The amplitude (A<sub>M2</sub>) and relative strength (RS<sub>M2</sub>) of the semi-diurnal lunar tidal component (M2) of TEC are analyzed. RS<sub>M2</sub> is the ratio between the energy of M2 and the energy of all the studied tidal components. The magnitudes of A<sub>M2</sub> and RS<sub>M2</sub> exhibit clear hemispheric and latitudinal variations. The A<sub>M2</sub> in the north of the magnetic equator tends to occur at lower magnetic latitudes than the A<sub>M2</sub> in the south of the magnetic equator. The RS<sub>M2</sub> exhibits similar features as the A<sub>M2</sub> but the difference is more distinct. We suggest that such hemispheric asymmetry of M2 parameters is related to the hemispheric asymmetry of the EIA and the latitudinal variation of the amplitude of the solar tidal components in winter.</p>

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