scholarly journals MoMo: a new empirical model of the Mars ionospheric total electron content based on Mars Express MARSIS data

2019 ◽  
Vol 9 ◽  
pp. A36 ◽  
Author(s):  
Nicolas Bergeot ◽  
Olivier Witasse ◽  
Sébastien Le Maistre ◽  
Pierre-Louis Blelly ◽  
Wlodek Kofman ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Empirical Model ◽  
Density Variation ◽  
Electron Content ◽  
Martian Surface ◽  
Total Electron ◽  
Mars Express ◽  
Radio Science ◽  
Ionosphere Model ◽  
The Impact

Aims: Several scientific landers and rovers have reached the Martian surface since the 1970s. Communication between the asset (i.e., lander or rover) and Mars orbiters or Earth antennas uses radio signals in UHF to X-band frequencies passing through the Mars’ ionosphere. It is consequently necessary to take into account electron density variation in the Mars’ ionosphere to correct the refraction of the signal transmitted. Methods: We developed a new empirical model of the Mars’ ionosphere called MoMo. It is based on the large database of Total Electron Content (TEC) derived from the subsurface mode of the Mars Express MARSIS radar. The model provides vertical TEC as a function of solar zenith angle, solar activity, solar longitude and location. For validation, the model is compared with Mars Express radio occultation data as well as with the numerical model IPIM (IRAP Plasmasphere-Ionosphere Model). Results: We discussed the output of the model in terms of climatology behaviour of the Mars’ ionosphere. The output of MoMo is then uses to quantify the impact of the Martian ionosphere for radio-science experiments. From our results, the effect is of the order of 10−3 mm s−1 in Doppler observables especially around sunrise and sunset. Consequently, this new model could be used to support the data analysis of any radio-science experiment and especially for present InSight RISE and futur ExoMars LARA instruments aiming at better understand the deep-interior of Mars.

scholarly journals Development of a local empirical model of ionospheric total electron content (TEC) and its application for studying solar-ionospheric effects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pantea Davoudifar ◽  
Keihanak Rowshan Tabari ◽  
Amir Abbas Eslami Shafigh ◽  
Ali Ajabshirizadeh ◽  
Zahra Bagheri ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Empirical Model ◽  
Solar Flares ◽  
Electron Content ◽  
Total Electron ◽  
Mean Values ◽  
Solar Origin ◽  
Solar Radio Flux ◽  
Ionosphere Model ◽  
Semi Empirical

AbstractRegular and irregular variations in total electron content (TEC) are one of the most significant observables in ionospheric studies. During the solar cycle 24, the variability of ionosphere is studied using global positioning system derived TEC at a mid-latitude station, Tehran (35.70N, 51.33E). Based on solar radio flux and seasonal and local time-dependent features of TEC values, a semi-empirical model is developed to represent its monthly/hourly mean values. Observed values of TEC and the results of our semi-empirical model then are compared with estimated values of a standard plasmasphere–ionosphere model. The outcome of this model is an expected mean TEC value considering the monthly/hourly regular effects of solar origin. Thus, it is possible to use it for monitoring irregular effects induced by solar events. As a result, the connection of TEC variations with solar activities are studied for the case of coronal mass ejections accompanying extreme solar flares. TEC response to solar flares of class X is well reproduced by this model. Our resulting values show that the most powerful flares (i.e. class X) induce a variation of more than 20 percent in daily TEC extent.

A new regional total electron content empirical model in northeast China

2016 ◽  
Vol 58 (7) ◽  
pp. 1155-1167 ◽  
Author(s):  
Jiandi Feng ◽  
Zhengtao Wang ◽  
Weiping Jiang ◽  
Zhenzhen Zhao ◽  
Bingbing Zhang
Keyword(s):  
Total Electron Content ◽  
Empirical Model ◽  
Northeast China ◽  
Electron Content ◽  
Total Electron

A new method for determining the total electron content in Mars’ ionosphere based on Mars Express MARSIS data

2020 ◽  
Vol 182 ◽  
pp. 104812
Author(s):  
Philip Conroy ◽  
Gary Quinsac ◽  
Nicolas Floury ◽  
Olivier Witasse ◽  
Marco Cartacci ◽  
...  
Keyword(s):  
Total Electron Content ◽  
New Method ◽  
Electron Content ◽  
Total Electron ◽  
Mars Express

scholarly journals Isolated ionospheric disturbances as deduced from global GPS network

2004 ◽  
Vol 22 (1) ◽  
pp. 47-62 ◽  
Author(s):  
E. L. Afraimovich ◽  
E. I. Astafieva ◽  
S. V. Voyeikov
Keyword(s):  
Total Electron Content ◽  
Acoustic Waves ◽  
Mean Value ◽  
Global Network ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Radio Science ◽  
Acoustic Gravity Waves ◽  
Medium Scale

Abstract. We investigate an unusual class of medium-scale traveling ionospheric disturbances of the nonwave type, isolated ionospheric disturbances (IIDs) that manifest themselves in total electron content (TEC) variations in the form of single aperiodic negative TEC disturbances of a duration of about 10min (the total electron content spikes, TECS). The data were obtained using the technology of global detection of ionospheric disturbances using measurements of TEC variations from a global network of receivers of the GPS. For the first time, we present the TECS morphology for 170 days in 1998–2001. The total number of TEC series, with a duration of each series of about 2.3h (2h18m), exceeded 850000. It was found that TECS are observed in no more than 1–2% of the total number of TEC series mainly in the nighttime in the spring and autumn periods. The TECS amplitude exceeds the mean value of the "background" TEC variation amplitude by a factor of 5–10 as a minimum. TECS represent a local phenomenon with a typical radius of spatial correlation not larger than 500km. The IID-induced TEC variations are similar in their amplitude, form and duration to the TEC response to shock-acoustic waves (SAW) generated during rocket launchings and earthquakes. However, the IID propagation velocity is less than the SAW velocity (800–1000m/s) and are most likely to correspond to the velocity of background medium-scale acoustic-gravity waves, on the order of 100–200m/s. Key words. Ionosphere (ionospheric irregularities, instruments and techniques) - Radio science (ionospheric propagation)

scholarly journals A New Global Total Electron Content Empirical Model

2019 ◽  
Vol 11 (6) ◽  
pp. 706 ◽  
Author(s):  
Jiandi Feng ◽  
Baomin Han ◽  
Zhenzhen Zhao ◽  
Zhengtao Wang
Keyword(s):  
Total Electron Content ◽  
Empirical Model ◽  
Single Point ◽  
Empirical Models ◽  
Electron Content ◽  
International Gnss Service ◽  
Prediction Ability ◽  
Total Electron ◽  
Grid Model ◽  
Grid Points

Research on total electron content (TEC) empirical models is one of the important topics in the field of space weather services. Global TEC empirical models based on Global Ionospheric Maps (GIMs) TEC data released by the International GNSS Service (IGS) have developed rapidly in recent years. However, the accuracy of such global empirical models has a crucial restriction arising from the non-uniform accuracy of IGS TEC data in the global scope. Specifically, IGS TEC data accuracy is higher on land and lower over the ocean due to the lack of stations in the latter. Using uneven precision GIMs TEC data as a whole for model fitting is unreasonable. Aiming at the limitation of global ionospheric TEC modelling, this paper proposes a new global ionospheric TEC empirical model named the TECM-GRID model. The model consists of 5183 sections, corresponding to 5183 grid points (longitude 5°, latitude 2.5°) of GIM. Two kinds of single point empirical TEC models, SSM-T1 and SSM-T2, are used for TECM-GRID. According to the locations of grid points, the SSM-T2 model is selected as the sub-model in the Mid-Latitude Summer Night Anomaly (MSNA) region, and SSM-T1 is selected as the sub-model in other regions. The fitting ability of the TECM-GRID model for modelling data was tested in accordance with root mean square (RMS) and relative RMS values. Then, the TECM-GRID model was validated and compared with the NTCM-GL model and Center for Orbit Determination in Europe (CODE) GIMs at time points other than modelling time. Results show that TECM-GRID can effectively describe the Equatorial Ionization Anomaly (EIA) and the MSNA phenomena of the ionosphere, which puts it in good agreement with CODE GIMs and means that it has better prediction ability than the NTCM-GL model.

scholarly journals Influence of the Ionosphere Model on the Solution of a VLBI Geodetic Experiment

1988 ◽  
Vol 129 ◽  
pp. 551-552
Author(s):  
G. Petit ◽  
J. F. Lestrade ◽  
C. Boucher ◽  
F. Biraud ◽  
A. Rius ◽  
...  
Keyword(s):  
South America ◽  
Total Electron Content ◽  
Dual Band ◽  
Single Frequency ◽  
Electron Content ◽  
Critical Aspect ◽  
Total Electron ◽  
Geodetic Vlbi ◽  
Ionosphere Model ◽  
First Time

The GRIG-2 geodetic VLBI experiment was conducted in 1985, linking for the first time South America, Europe and Africa. At the single frequency band of 1.66 GHz which was used, the monitoring of the ionosphere is a critical aspect and several predictions of Total Electron Content (TEC) were used. One of them is derived from dual band Doppler observations of TRANSIT satellites, which were simultaneously conducted. The influence of these models on the solution is presented, with comparisons with other VLBI solutions. Decimetric accuracy has been achieved.

scholarly journals An empirical model of ionospheric total electron content (TEC) near the crest of the equatorial ionization anomaly (EIA)

2016 ◽  
Vol 6 ◽  
pp. A29 ◽  
Author(s):  
Rajkumar Hajra ◽  
Shyamal Kumar Chakraborty ◽  
Bruce T. Tsurutani ◽  
Ashish DasGupta ◽  
Ezequiel Echer ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Empirical Model ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Total Electron Content ◽  
Equatorial Ionization Anomaly

Improving Total Electron Content (TEC) Models for Geodetic Applications

2020 ◽  
Author(s):  
Mona Kosary ◽  
Saeed Farzaneh ◽  
Maike Schumacher ◽  
Ehsan Forootan
Keyword(s):  
Data Assimilation ◽  
Total Electron Content ◽  
Precise Point Positioning ◽  
Main Tool ◽  
Model Parameters ◽  
Electron Content ◽  
Total Electron ◽  
Radio Science ◽  
Imperfect Knowledge ◽  
Point Positioning

<p>Increasing the quality of ionosphere modeling is crucial and remains a challenge for many geodetic applications such as GNSS Precise Point Positioning (PPP) and navigation. Ionosphere models are the main tool to provide an estimation of Total Electron Content (TEC) to be corrected from GNSS career phase and pseudorange measurements. Skills of these models are however limited due to the simplifications in model equations and the imperfect knowledge of model parameters. In this study, an ionosphere reconstruction approach is presented, where global estimations of geodetic-based TEC measurements are combined with an ionospheric background model. This is achieved here through a novel simultaneous Calibration and Data Assimilation (C/DA) technique that works based on the sequential Ensemble Kalman Filter (EnKF). The C/DA method ingests the actual ionospheric measurements (derived from global GNSS measurements) into the IRI (International Reference Ionosphere) model. It also calibrates those parameters that control the F2 layer’s characteristics such as selected important CCIR (Comité Consultatif International des Radiocommunicationsand) URSI (International Union of Radio Science) coefficients.  The calibrated parameters derived from the C/DA are then replaced in the IRI to simulate TEC values in locations, where less GNSS ground-station infrastructure exists, as well as to enhance the prediction of TEC when the observations are not available or their usage is cautious due to low quality. Our numerical assessments indicate the advantage of the C/DA to improve the IRI’s performance. Values of the TEC-Root Mean Square of Error (RMSE) are found to be decreased by up to 30% globally, compared to the original IRI simulations. The importance of the new TEC estimations is demonstrated for PPP applications, whose results show improvements in navigation applications.</p><p><strong>Keywords: </strong>Ionosphere, Calibration and Data Assimilation (C/DA), IRI, Total Electron Content (TEC), Precise Point Positioning (PPP), GNSS</p>

A Data Assimilated Regional Ionosphere Model Using the Total Electron Content from the Korean GPS Network

2018 ◽  
Vol 72 (7) ◽  
pp. 826-834 ◽  
Author(s):  
Chalachew Kindie Mengist ◽  
Yong Ha Kim ◽  
Nicholas Ssessanga ◽  
Jeong-Heon Kim
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Total Electron ◽  
Ionosphere Model ◽  
Gps Network
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