IONORING: Real-Time Monitoring of the Total Electron Content over Italy

IONORING (IONOspheric RING) is a tool capable to provide the real-time monitoring and modeling of the ionospheric Total Electron Content (TEC) over Italy, in the latitudinal and longitudinal ranges of 35°N–48°N and 5°E–20°E, respectively. IONORING exploits the Global Navigation Satellite System (GNSS) data acquired by the RING (Rete Integrata Nazionale GNSS) network, managed by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The system provides TEC real-time maps with a very fine spatial resolution (0.1° latitude x 0.1° longitude), with a refresh time of 10 min and a typical latency below the minute. The TEC estimated at the ionospheric piercing points from about 40 RING stations, equally distributed over the Italian territory, are interpolated using locally (weighted) regression scatter plot smoothing (LOWESS). The validation is performed by comparing the IONORING TEC maps (in real-time) with independent products: (i) the Global Ionospheric Maps (GIM) - final product- provided by the International GNSS Service (IGS), and (ii) the European TEC maps from the Royal Observatory of Belgium. The validation results are satisfactory in terms of Root Mean Square Error (RMSE) between 2 and 3 TECu for both comparisons. The potential of IONORING in depicting the TEC daily and seasonal variations is analyzed over 3 years, from May 2017 to April 2020, as well as its capability to account for the effect of the disturbed geospace on the ionosphere at mid-latitudes. The IONORING response to the X9.3 flare event of September 2017 highlights a sudden TEC increase over Italy of about 20%, with a small, expected dependence on the latitude, i.e., on the distance from the subsolar point. Subsequent large regional TEC various were observed in response to related follow-on geomagnetic storms. This storm is also used as a case event to demonstrate the potential of IONORING in improving the accuracy of the GNSS Single Point Positioning. By processing data in kinematic mode and by using the Klobuchar as the model to provide the ionospheric correction, the resulting Horizontal Positioning Error is 4.3 m, lowering to, 3.84 m when GIM maps are used. If IONORING maps are used as the reference ionosphere, the error is as low as 2.5 m. Real-times application and services in which IONORING is currently integrated are also described in the conclusive remarks.

[1]  O. J. Olwendo,et al.  Validation of NeQuick 2 model over the Kenyan region through data ingestion and the model application in ionospheric studies , 2016 .

[2]  A. Garcia-Rigo,et al.  The IGS VTEC maps: a reliable source of ionospheric information since 1998 , 2009 .

[3]  Gang Wang,et al.  Evaluation of COMPASS ionospheric model in GNSS positioning , 2013 .

[4]  Dongsheng Zhao,et al.  Modeling Australian TEC Maps Using Long-Term Observations of Australian Regional GPS Network by Artificial Neural Network-Aided Spherical Cap Harmonic Analysis Approach , 2020, Remote. Sens..

[5]  Andrzej Krankowski,et al.  IGS real-time service for global ionospheric total electron content modeling , 2020, Journal of Geodesy.

[6]  Libo Liu,et al.  A brief review of equatorial ionization anomaly and ionospheric irregularities , 2018 .

[7]  Claudio Brunini,et al.  GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions , 2010 .

[8]  Vincenzo Romano,et al.  The ionospheric irregularities climatology over Svalbard from solar cycle 23 , 2019, Scientific Reports.

[9]  Harald Schuh,et al.  Performance Evaluation of VTEC GIMs for Regional Applications during Different Solar Activity Periods, Using RING TEC Values , 2021, Remote. Sens..

[10]  Sandro M. Radicella,et al.  Calibration errors on experimental slant total electron content (TEC) determined with GPS , 2007 .

[11]  Michael Pezzopane,et al.  On some features characterizing the plasmasphere–magnetosphere–ionosphere system during the geomagnetic storm of 27 May 2017 , 2019, Earth, Planets and Space.

[12]  R. Roble.  The calculated and observed diurnal variation of the ionosphere over Millstone Hill on 23–24 March 1970 , 1975 .

[13]  Andrzej Krankowski,et al.  Methodology and consistency of slant and vertical assessments for ionospheric electron content models , 2017, Journal of Geodesy.

[14]  Bruno Bougard,et al.  L-band scintillations and calibrated total electron content gradients over Brazil during the last solar maximum , 2015 .

[15]  G. De Franceschi,et al.  Ionospheric mapping by regional spherical harmonic analysis: New developments , 1994 .

[16]  Y. Yuan,et al.  Auto-covariance estimation of variable samples (ACEVS) and its application for monitoring random ionospheric disturbances using GPS , 2001 .

[17]  Adrià Rovira-Garcia,et al.  Assessing the quality of ionospheric models through GNSS positioning error: methodology and results , 2019, GPS Solutions.

[18]  Zhe Yang,et al.  Geomagnetic Storm Induced Mid-latitude Ionospheric Plasma Irregularities and Their Implications for GPS Positioning over North America: A Case Study , 2020, 2020 IEEE/ION Position, Location and Navigation Symposium (PLANS).

[19]  Claudio Cesaroni,et al.  Does TEC react to a sudden impulse as a whole? The 2015 Saint Patrick’s day storm event , 2017 .

[20]  Eric Pottiaux,et al.  Near real-time ionospheric monitoring over Europe at the Royal Observatory of Belgium using GNSS data , 2014 .

[21]  Bodo W. Reinisch,et al.  Global Ionospheric Radio Observatory (GIRO) , 2011 .

[22]  Yunbin Yuan,et al.  The BeiDou global broadcast ionospheric delay correction model (BDGIM) and its preliminary performance evaluation results , 2019, Navigation.

[23]  Marcio Aquino,et al.  The ionosphere prediction service prototype for GNSS users , 2019, Journal of Space Weather and Space Climate.

[24]  Irina Zakharenkova,et al.  Towards Cooperative Global Mapping of the Ionosphere: Fusion Feasibility for IGS and IRI with Global Climate VTEC Maps , 2020, Remote. Sens..

[25]  W. Cleveland.  Robust Locally Weighted Regression and Smoothing Scatterplots , 1979 .

[26]  Zhizhao Liu,et al.  Challenges to Equatorial Plasma Bubble and Ionospheric Scintillation Short-Term Forecasting and Future Aspects in East and Southeast Asia , 2020, Surveys in Geophysics.

[27]  O. J. Olwendo,et al.  Equatorial ionospheric disturbances over the East African sector during the 2015 St. Patrick’s day storm , 2017 .

[28]  Jaume Sanz,et al.  EGNOS 1046 Maritime Service Assessment , 2020, Sensors.

[29]  Bruno Zolesi,et al.  Regional mapping of the critical frequency of the F2 layer by spherical cap harmonic expansion , 1991 .

[30]  H. Lühr,et al.  The magnitude and inter-hemispheric asymmetry of equatorial ionization anomaly-based on CHAMP and GRACE observations , 2013 .

[31]  Lee-Anne McKinnell,et al.  Development of a regional GPS-based ionospheric TEC model for South Africa , 2007 .