## Scientific and technological production Ordered by:  Date asc. Date desc. Title asc. Title desc. Researcher asc. Researcher desc.

1 to 50 of 836 results
• SHPTS: towards a new method for generating precise global ionospheric TEC map based on spherical harmonic and generalized trigonometric series functions

Li, Zishen; Yuan, Yunbin; Wang, Ningbo; Hernandez Pajares, Manuel; Huo, Xingliang
Journal of geodesy
Vol. 89, num. 4, p. 331-345
DOI: 10.1007/s00190-014-0778-9
Date of publication: 2015-04
Journal article

To take maximum advantage of the increasing Global Navigation Satellite Systems (GNSS) data to improve the accuracy and resolution of global ionospheric TEC map (GIM), an approach, named Spherical Harmonic plus generalized Trigonometric Series functions (SHPTS), is proposed by integrating the spherical harmonic and the generalized trigonometric series functions on global and local scales, respectively. The SHPTS-based GIM from January 1st, 2001 to December 31st, 2011 (about one solar cycle) is validated by the ionospheric TEC from raw global GPS data, the GIM released by the current Ionospheric Associate Analysis Center (IAAC), the TOPEX/Poseidon satellite and the DORIS. The present results show that the SHPTS-based GIM over the area where no real data are available has the same accuracy level (approximately 2–6 TECu) to that released by the current IAAC. However, the ionospheric TEC in the SHPTS-based GIM over the area covered by real data is more accurate (approximately 1.5 TECu) than that of the GIM (approximately 3.0 TECu) released by the current IAAC. The external accuracy of the SHPTS-based GIM validated by the TOPEX/Poseidon and DORIS is approximately 2.5–5.5 and 1.5–4.5 TECu, respectively. In particular, the SHPTS-based GIM is the best or almost the best ranked, along with those of JPL and UPC, when they are compared with TOPEX/Poseidon measurements, and the best (in addition to UPC) when they are validated with DORIS data. With the increase in the number of GNSS satellites and contributing stations, the performance of the SHPTS-based GIM can be further improved. The SHPTS-based GIM routinely calculated using global GPS, GLONASS and BDS data will be found at the website http://www.gipp.org.cn.

• Statistical characterization of strong and mid solar flares and sun EUV rate monitoring with GNSS

Monte Moreno, Enrique; Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Beniguel, Yannick; Orús Pérez, Raul; Prieto Cerdeira, Roberto; Schlueter, Stefan
Geophysical research abstracts
Vol. 17, p. 1
Date of publication: 2015-03-16
Journal article

The global network of permanent Global Navigation Satellite Systems (GNSS) receivers has become an useful and affordable way of monitoring the Solar EUV flux rate, especially -for the time being- in the context of Major and Mid geoeffective intensity Solar Flares (M. Hernandez-Pajares et al., SpaceWeather, doi:10.1029/2012SW000826, 2012). In fact the maturity of this technique (GNSS Solar FLAre Indicator, GSFLAI) has allowed to incorporate it in operational real-time (RT) conditions, thanks to the availability of global GNSS datastreams from the RT International GNSS Network (M. Caissy et al, GPS World, June 1, 2012), and performed in the context of the MONITOR and MONITOR2 ESA-funded projects (Y. Beniguel et al., NAVITEC Proc., 978-1-4673-2011-5 IEEE, 2012). The main goal of this presentation is to summarize a detailed recent study of the statistical properties of Solar Flares (E. Monte and M. Hernandez-Pajares, J. Geophys. Res., doi:10.1002/2014JA020206, 2014) by considering the GNSS proxy of EUV rate (GSFLAI parameter) computed independently each 30 seconds during the whole last solar cycle. An statistical model has been characterized that explains the empirical results such as (a) the persistence and presence of bursts of solar flares and (b) their long tail peak values of the solar flux variation, which can be characterized by: (1) A fractional Brownian model for the long-term dependence, and (2), a power law distribution for the time series extreme values. Finally, an update of the Solar Flares’ occurrence during the recent months of Solar Activity, gathered in RT within MONITOR2 project, will close the paper.

• Internal report. Spectral methods for time delay estimation of MSTIDs signal

Yang, Heng; Monte Moreno, Enrique; Hernandez Pajares, Manuel
Date: 2015-02-14
Report

The primary goal of this work is to summarize spectral meth- ods to estimate the time delay variations of the detrended Medium Scale Traveling Ionospheric Disturbances (MSTIDs) signals and pre- liminarily discuss the potential infuence of the Doppler efects. The MSTIDs signals are assumed as the planar waves with the wavelength between 10-100 kilometers, which are measured from a local high- dense receivers Global Navigation Satellite System (GNSS) network for a given satellite. The signals show strong correlation with each others in the whole observation time series. The time delay of the detrended MSTIDs signals preprocessed with a specic overlapped sliding window can be estimated by several techniques. The data con- sisted on two detrended MSTIDs signals measured from the GNSS data on the day 1, 2011 obtained from the small area network in Cal- ifornia. In this paper we have implemented the following methods in order to estimate the time delay between signals: (1) Generalized cross correlation method, which estimates the time delay in time do- main after the inverse Fourier transform of appropriately weighted cross power spectrum density, (2) generalized phase spectrum method directly measured from the appropriately weighted cross power spec- trum density, (3) phase spectrum dierence method calculated ap- proximately from the fundamental waves of the signals. The results with dierent methods show the similar variation of time delay of two MSTIDs signals. In addition, with the phase spectrum method, the results can present the clear frequency variation of MSTIDs signals which may be in uenced by potential Doppler eect. Note that the correct estimate of the delays required of a preprocessing of the data. The rst dierence of the Vertical Total Electron Contents (dVTEC) signal was preprocessed by modeling the eect of the displacement of the satellite by means of a parabolic component, which is subtracted, following by detrend of 60-second intervals, decimation and a further low pass ltering process.

The primary goal of this work is to summarize spectral meth- ods to estimate the time delay variations of the detrended Medium Scale Traveling Ionospheric Disturbances (MSTIDs) signals and pre- liminarily discuss the potential infuence of the Doppler e fects. The MSTIDs signals are assumed as the planar waves with the wavelength between 10-100 kilometers, which are measured from a local high- dense receivers Global Navigation Satellite System (GNSS) network for a given satellite. The signals show strong correlation with each others in the whole observation time series. The time delay of the detrended MSTIDs signals preprocessed with a speci c overlapped sliding window can be estimated by several techniques. The data con- sisted on two detrended MSTIDs signals measured from the GNSS data on the day 1, 2011 obtained from the small area network in Cal- ifornia. In this paper we have implemented the following methods in order to estimate the time delay between signals: (1) Generalized cross correlation method, which estimates the time delay in time do- main after the inverse Fourier transform of appropriately weighted cross power spectrum density, (2) generalized phase spectrum method directly measured from the appropriately weighted cross power spec- trum density, (3) phase spectrum di erence method calculated ap- proximately from the fundamental waves of the signals. The results with di erent methods show the similar variation of time delay of two MSTIDs signals. In addition, with the phase spectrum method, the results can present the clear frequency variation of MSTIDs signals which may be in uenced by potential Doppler e ect. Note that the correct estimate of the delays required of a preprocessing of the data. The rst di erence of the Vertical Total Electron Contents (dVTEC) signal was preprocessed by modeling the e ect of the displacement of the satellite by means of a parabolic component, which is subtracted, following by detrend of 60-second intervals, decimation and a further low pass ltering process.

• The 2013 Ibiza calibration campaign of Jason-2 and Saral altimeters

Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Martinez Benjamin, Juan Jose; Mercier, Flavien; Pérosanz, Felix; Gárate Pasquín, Jorge; Martin Davila, José; Pérez Gómez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Hernandez Pajares, Manuel; Salazar, Mario; Bonnefond, Pascal; Valles Casanova, I. Berenguer
Marine geodesy
DOI: 10.1080/01490419.2015.1008711
Date of publication: 2015-02-09
Journal article

This study presents the results of the 2013 Ibiza (Western Mediterranean) calibration campaign of Jason-2 and SARAL altimeters. It took place from 14 to 16 September 2013 and was composed of two phases: the calibration of the GNSS (Global Navigation Satellite System) buoys to estimate the antenna height of each of them and absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was at ˜ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and SARAL nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and SARAL respectively. The GNSS data were processed using precise point positioning technique. The biases found are of (-0.1 ± 0.9) and (-3.1 ± 1.5) cm for Jason-2 and SARAL respectively.

• Internal report. Numerical methods for medium scale traveling ionospheric disturbances signal pre-processing

Yang, Heng; Monte Moreno, Enrique; Hernandez Pajares, Manuel
Date: 2015-01-15
Report

In this paper we discuss the eects of several signal preprocessing methods for enhancing the Medium Scale Traveling Ionospheric Dis- turbances (MSTIDs) signal. The MSTIDs signal are the ionospheric signatures of waves with a typical scale variation from 50 to 300 m/s, which can be detected and modeled from variation of the ionospheric Vertical Total Electron Content (VTEC) with dual-frequency mea- surements of Global Navigation Satellite Systems (GNSS). In order to enhance the useful information of the signal, and also reduce the noise, we purpose the use of dierent numerical methods for preprocessing the MSTIDs signal. A rst approach to preprocessing the signal is a simple high-pass ltering or Slant Total Electron Content (STEC) detrending of the ionospheric carrier phase LI [see Hernndez-Pajares et al. 2006, Hernndez-Pajares et al. 2012]. In this work, we propose the following signal processing steps in order to enhance the signal: (1) Parabolic subtraction adopted in eliminating the typical geometric length variation within the ionosphere carrier phase LI, (2) decima- tion techniques used to instead of classic STEC detrending method, (3) low pass ltering adapted to the properties of the desired signal. From the results by testing the observing data on the day 1, 2011 obtained from the small area GNSS network in California, it's shown that the MSTIDs signal after preprocessing techniques are more clear, smooth and robust.

In this paper we discuss the e ects of several signal preprocessing methods for enhancing the Medium Scale Traveling Ionospheric Dis- turbances (MSTIDs) signal. The MSTIDs signal are the ionospheric signatures of waves with a typical scale variation from 50 to 300 m/s, which can be detected and modeled from variation of the ionospheric Vertical Total Electron Content (VTEC) with dual-frequency mea- surements of Global Navigation Satellite Systems (GNSS). In order to enhance the useful information of the signal, and also reduce the noise, we purpose the use of di erent numerical methods for preprocessing the MSTIDs signal. A rst approach to preprocessing the signal is a simple high-pass ltering or Slant Total Electron Content (STEC) detrending of the ionospheric carrier phase LI [see Hernndez-Pajares et al. 2006, Hernndez-Pajares et al. 2012]. In this work, we propose the following signal processing steps in order to enhance the signal: (1) Parabolic subtraction adopted in eliminating the typical geometric length variation within the ionosphere carrier phase LI, (2) decima- tion techniques used to instead of classic STEC detrending method, (3) low pass ltering adapted to the properties of the desired signal. From the results by testing the observing data on the day 1, 2011 obtained from the small area GNSS network in California, it's shown that the MSTIDs signal after preprocessing techniques are more clear, smooth and robust.

• Use of GNSS derived ionospheric information to detect and measure Solar Flares

Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Aragon Angel, Maria Angeles
Física de la Tierra
Vol. 26, num. 2014, p. 81-87
Date of publication: 2014-12
Journal article

The Ionosphere, the partially ionized atmospheric r egion ranging from approximately 60 to +1000 km height, is typically affected by spatial and tempor al variations, driven by Local Time (solar illumina - tion), Latitude (magnetic field and solar illuminat ion) and time (space weather, among seasonal and solar cycle dependence). It can be indirectly studi ed from the dual L-band frequency GNSS measure- ments by assuming the first order ionospheric delay approximation (the higher order ionospheric effects in GNSS typically constitute less than 0.1% of the overall ionospheric effect and only affects very precise applications). Moreover, the Ionospher e is affected as well by ionospheric waves, ,solar flares and other space weather effects. Recent mode ling techniques and corresponding results are going to be summarized regarding to the daylight su dden overionization generated by the radiation associated to Solar Flares facing the Earth, and it s measurement by means of Global Navigation Satellite Systems. This approach has already been i mplemented in real-time by the authors.

• Internal report. Solving mixed integer non-linear programming problem applied to GNSS data

Yang, Heng; Monte Moreno, Enrique; Hernandez Pajares, Manuel
Date: 2014-11-07
Report

The purpose of this paper is to characterize Medium Scale Trav- eling Ionospheric Disturbances (MSTIDs), by means of Mixed Integer Nonlinear Programming (MINLP). The MINLP techniques are used to for estimating the parameters of the equations that describe the MSTIDs from a set of observations. A new MSTIDs wave detecting method, which we will denote as Ambiguity Resolution in Global Navi- gational Satellite System (GNSS) Ionospheric Interferometry (ARGII) technique, is designed to model the MSTIDs wave with the data from the wide low-density GNSS receivers network. The ARGII techniques can be set as an special instance of MINLP, because the problem is set as a series of MSTIDs equations including the unknown wave veloc- ity (continuous) and cycle ambiguities (integers). The performance of heuristic and direct search optimization algorithms are evaluated by solving the MINLP problem with techniques bared an dierent prin- ciples, and as benchmark we use the solution obtained by exhaustive enumeration of all possible integer solutions. Among the algorithms we have implemented in this work are genetic algorithm, simulated annealing, particle swarm, pattern search and Nelder Mead methods. The GNSS data used to test the these solvers is observed from the wide GNSS network in the north of Poland on the day 353, 2013 whose di- ameter is more than the half of wavelength and therefore will have phase ambiguities. The evaluating experiments show that the results computed by the simple improved optimization algorithms especially the Nelder Mead have not only high correlations with the reference method (i.e. exhaustive enumeration) but also extremely lower time complexity compared to the benchmark method. Despite unguaran- teed global optimal results for the MINLP problems, these methods show the excellent performance in time complexity when computing the velocities of MSTIDs with ARGII techniques from large quantity of the GNSS data.

The purpose of this paper is to characterize Medium Scale Trav- eling Ionospheric Disturbances (MSTIDs), by means of Mixed Integer Nonlinear Programming (MINLP). The MINLP techniques are used to for estimating the parameters of the equations that describe the MSTIDs from a set of observations. A new MSTIDs wave detecting method, which we will denote as Ambiguity Resolution in Global Navi- gational Satellite System (GNSS) Ionospheric Interferometry (ARGII) technique, is designed to model the MSTIDs wave with the data from the wide low-density GNSS receivers network. The ARGII techniques can be set as an special instance of MINLP, because the problem is set as a series of MSTIDs equations including the unknown wave veloc- ity (continuous) and cycle ambiguities (integers). The performance of heuristic and direct search optimization algorithms are evaluated by solving the MINLP problem with techniques bared an di erent prin- ciples, and as benchmark we use the solution obtained by exhaustive enumeration of all possible integer solutions. Among the algorithms we have implemented in this work are genetic algorithm, simulated annealing, particle swarm, pattern search and Nelder Mead methods. The GNSS data used to test the these solvers is observed from the wide GNSS network in the north of Poland on the day 353, 2013 whose di- ameter is more than the half of wavelength and therefore will have phase ambiguities. The evaluating experiments show that the results computed by the simple improved optimization algorithms especially the Nelder Mead have not only high correlations with the reference method (i.e. exhaustive enumeration) but also extremely lower time complexity compared to the benchmark method. Despite unguaran- teed global optimal results for the MINLP problems, these methods show the excellent performance in time complexity when computing the velocities of MSTIDs with ARGII techniques from large quantity of the GNSS data.

• Occurrence of solar flares viewed with GPS: statistics and fractal nature

Monte Moreno, Enrique; Hernandez Pajares, Manuel
Journal of geophysical research: space physics
Vol. 119, num. 11, p. 9216-9227
DOI: 10.1002/2014JA020206
Date of publication: 2014-11-01
Journal article

In this paper we describe the statistical properties of the EUV solar flux sudden variation. The solar flux variation is modeled as a time series characterized by the subsolar Vertical Total Electron Content double difference in time, computed with dual-frequency GNSS (Global Navigation Satellite Systems) measurements in the daylight hemisphere (GNSS solar flare indicator rate parameter). We propose a model that explains its characteristics and the forecasting limitations. The sudden overionization pattern is assumed to be of solar origin, and the data used in this study was collected during the last solar cycle. The two defining characteristics of this time series are an extreme variability (i.e., in a solar cycle one can find events at 400 sigma from the mean value) and a temporal correlation that is independent of the timescale. We give a characterization of a model that explains the empirical results and properties such as (a) the persistence and presence of bursts of solar flares and (b) their long tail peak values of the solar flux variation. We show that the solar flux variation time series can be characterized by a fractional Brownian model for the long-term dependence, and a power law distribution for the extreme values that appear in the time series.

• INSPIRE - IoNosphere Sounding for Pre-seismic anomalies Identification REsearch

Krankowski, Andrzej; Hernandez Pajares, Manuel; Rothkael, Hanna; Garcia Rigo, Alberto; Rojas Gregorio, Jose Ignacio
Competitive project

• HORION - Higher Order Ionospheric Modelling Campaigns for precise GNSS applications

Pucilowski, Marcin; Portasiak, Krystian; Bosy, Jaroslaw; Szyszko, Robert; Wielgosz, Pawel; Hernandez Pajares, Manuel; Kaplon, Jan; Hadas, Tomasz; Paziewski, Jacek; Krypiak-Gregorczyk, Anna; Stepniak, Katarzyna; Krukowska, Marta; Garcia Rigo, Alberto
Competitive project

• Absolute calibration of Jason-2 and Saral during the 2013 Ibiza calibration campaign

Martinez Benjamin, Juan Jose; Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Pérosanz, Felix; Gárate Pasquín, Jorge; Martin Davila, José; Pérez Gómez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Gonzalez Gonzalez, Juan Carlos; Salazar Lino, Mário; Hernandez Pajares, Manuel; Sanz Conde, M. Mercedes; Valles Casanova, I. Berenguer
Ocean Surface Topography Science Team Meeting
p. 207
Presentation's date: 2014-10
Presentation of work at congresses

An altimetry calibration campaign was achieved in the Mediterranean Sea, close to the Ibiza island (Baleares) area, last September in the framework of a Spanish-French cooperation. Its goal was to provide absolute biases for the Jason-2 and AltiKa/Saral altimeters through comparisons with GNSS measurements on buoys. A similar Spanish/French experiment was already performed for Jason-1in June 2003 in this geographical area under the name IBIZA 2003 campaign. Direct absolute altimeter calibration, estimating the Jason-2 and AltiKa/Saral biases, was made from direct overflights using GPS buoys. This method does not require any modelling of geoid and tidal error. The crossover point between Jason-2 and Saral North of Ibiza (around 40 nm) and West of Mallorca island was found to be optimal for our purposes as it allows measurements at a one-day time-lag and a similar configuration of buoys for each satellite pass. 5 buoys were deployed near a Jason-2/AltiKA Saral crossover point to determine the sea surface in the along-track and cross-track directions, to estimate by interpolation the exact nadir point of the satellite. Here, we present the experimental settings of the campaign and the datasets used in this study, the methods used for comparing altimetry data with GNSS measurements, and the first results of the absolute calibration.

• Extended version. Occurrence of solar flares viewed with GPS: statistics and fractal nature

Monte Moreno, Enrique; Hernandez Pajares, Manuel
Date: 2014-09-05
Report

In this paper we describe the statistical properties of the EUV solar flux sudden variation. The solar flux variation is modeled as a time series characterized by the subsolar VTEC (Vertical Total Electron Content) double-difference in time, computed with dual frequency GNSS (Global Navigation Satellite System) measurements in the daylight hemisphere. By assuming a sudden overionization pattern of solar origin, during the last solar cycle, we propose a model that explains it's characteristics, and the forecasting limitations. The two defining characteristics of this time series, is an extreme variability (i.e.\ in a solar cycle one can find events at $400 \sigma$ from the mean value) and a temporal correlation that is independent of the time scale. We give a characterization of a model that explains the empirical results, and properties such as, a) the persistence and presence of bursts of solar flares, b) their long tail peak values of the solar flux variation. We show that the solar flux variation time series can be characterized by a fractional Brownian model for the long term dependence, and a powerlaw distribution for the extreme values that appear in the time series.

• Simultaneous real-time global electron content determination and solar EUV flux monitoring thanks to the RT-IGS global network data streams

Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Prieto Cerdeira, Roberto; Orús Pérez, Raul; Beniguel, Yannick; Caissy, Mark; Agrotis, Lukas; Weber, Georg
Scientific Assembly of the Committee on Space Research
p. 1
Presentation's date: 2014-08-05
Presentation of work at congresses

The availability of real-time GNSS datastreams from the Real-Time International GNSS Service (RT-IGS) has enabled new and improved applications in geoscience and engineering, for such network of global continuously operating reference stations. We are going to summarize two of them, developed by UPC-IONSAT and supported by the European Space Agency (ESA), among RT-IGS. On the one hand, UPC-IONSAT has developed a first RT version of its ionospheric electron content data driven model (RT-TOMION) in the frame of the Real Time International GNSS Service (RT-IGS) as ionospheric analysis center (see “Caissy M. et al.: The International GNSS Real-Time Service, GPS World, June 2012”). RT-TOMION is directly fed by RT-IGS observations and solved thanks to a combined Tomographic-Kriging technique, which is continuously running in real-time mode as in the case of datastreams. So far its performance has been mainly limited by the reduced, though increasing, number of worldwide GNSS receivers with availability of data in real-time. On the other hand, considering the same RT-IGS datastreams, UPC-IONSAT has been monitoring the solar EUV flux in real-time, by means of a new technique that has been recently developed (“Hernández-Pajares M. et al., GNSS measurement of EUV photons flux rate during strong and mid solar flares, Space weather,10-12, pp. 1-16, 2012”). In fact, monitoring of the rapid variation of the EUV solar flux is directly providing warnings of Solar Flare alarms (among other ionospheric variability indices), in the context of ESA’s MONITOR project, intended for the study of the Solar Cycle maximum, and its influence on GNSS services. In this context, a summary of the performance of both real-time systems, which are fed simultaneously with the same global RT GNSS data, is presented. The emphasis would be on its present strengths, additional potentialities and applications. The quality of the results will be characterized by means of direct comparisons with independent reference data, such as dual-frequency altimeter measurements (for RT-Vertical Electron Content), and direct measurements from dedicated solar probes (for the retrieval of EUV solar flux rate).

• North-south components of the annual asymmetry in the ionosphere

Gulyaeva, Tamara L.; Arikan, Feza; Hernandez Pajares, Manuel; Veselovsky, I.S.
Vol. 49, num. 7, p. 485-496
DOI: 10.1002/2014RS005401
Date of publication: 2014-07-01
Journal article

A retrospective study of the asymmetry in the ionosphere during the solstices is made using the different geospace parameters in the North and South magnetic hemispheres. Data of total electron content (TEC) and global electron content (GEC) produced from global ionospheric maps, GIM-TEC for 1999-2013, the ionospheric electron content (IEC) measured by TOPEX-Jason 1 and 2 satellites for 2001-2012, the F-2 layer critical frequency and peak height measured on board ISIS 1, ISIS 2, and IK19 satellites during 1969-1982, and the earthquakes M5+ occurrences for 1999-2013 are analyzed. Annual asymmetry is observed with GEC and IEC for the years of observation with asymmetry index, AI, showing January > July excess from 0.02 to 0.25. The coincident pattern of January-to-July asymmetry ratio of TEC and IEC colocated along the magnetic longitude sector of 270 degrees +/- 5 degrees E in the Pacific Ocean is obtained varying with local time and magnetic latitude. The sea/land differences in the F-2 layer peak electron density, NmF2, and the peak height, h(m)F(2), gathered with topside sounding data exhibit tilted ionosphere along the seashores with denser electron population at greater peak heights over the sea. The topside peak electron density NmF2, TEC, IEC, and the hemisphere part of GEC are dominant in the South hemisphere which resembles the pattern for seismic activity with dominant earthquake occurrence in the South magnetic hemisphere. Though the study is made for the hemispheric and annual asymmetry during solstices in the ionosphere, the conclusions seem valid for other aspects of seismic-ionospheric associations with tectonic plate boundaries representing zones of enhanced risk for space weather.

• MONITOR 2 - Ionospheric Monitoring Network (CCN Proposal in response to ESA EGEP ID 63.3)

Beniguel, Yannick; Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Nava, Bruno; van de Kamp, Max; Kauristie, Kirsti; Berdermann, Jens; Wilken, Volker; Monnerat, Michel; Serant, Damien; Krankowski, Andrzej; Grosu, Alex; Scortan, Sorin; Popescu, Florian
Competitive project

• KRIIM - Korean Improved Ionospheric Model

Hernandez Pajares, Manuel; Olivares Pulido, German; Garcia Rigo, Alberto
Competitive project

• Distribution and mitigation of higher-order ionospheric effects on precise GNSS processing

Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Defraigne, Pascale; Bergeot, Nicolas; Prieto Cerdeira, Roberto; Garcia Rigo, Alberto
Journal of geophysical research B: solid earth
Vol. 119, num. 4, p. 3823-3837
DOI: 10.1002/2013JB010568
Date of publication: 2014-04
Journal article

Higher-order ionospheric effects (I2+) are one of the main limiting factors in very precise Global Navigation Satellite Systems (GNSS) processing, for applications where millimeter accuracy is demanded. This paper summarizes a comprehensive study of the I2+ effects in range and in GNSS precise products such as receiver position and clock, tropospheric delay, geocenter offset, and GNSS satellite position and clock. All the relevant higher-order contributions are considered: second and third orders, geometric bending, and slant total electron content (dSTEC) bending (i.e., the difference between the STEC for straight and bent paths). Using a realistic simulation with representative solar maximum conditions on GPS signals, both the effects and mitigation errors are analyzed. The usage of the combination of multifrequency L band observations has to be rejected due to its increased noise level. The results of the study show that the main two effects in range are the second-order ionospheric and dSTEC terms, with peak values up to 2 cm. Their combined impacts on the precise GNSS satellite products affects the satellite Z coordinates (up to +1 cm) and satellite clocks (more than ±20 ps). Other precise products are affected at the millimeter level. After correction the impact on all the precise GNSS products is reduced below 5 mm. We finally show that the I2+ impact on a Precise Point Positioning (PPP) user is lower than the current uncertainties of the PPP solutions, after applying consistently the precise products (satellite orbits and clocks) obtained under I2+ correction

• PIOM-FIPP - Experimental Campaigns Design report (ECD)

Stepniak, Katarzyna; Paziewski, Jacek; Wielgosz, Pawel; Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Bosy, Jaroslaw; Hadas, Tomasz; Krypiak-Gregorczyk, Anna
Date: 2014-03-20
Report

• PIOM-FIPP - State of the Art and potential improvements in precise ionospheric, tropospheric and position estimation with GNSS

Paziewski, Jacek; Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Bosy, Jaroslaw; Hadas, Tomasz; Krypiak-Gregorczyk, Anna; Wielgosz, Pawel
Date: 2014-02-03
Report

• UPC contribution to MONITOR CCN

Hernandez Pajares, Manuel; Garcia Rigo, Alberto
Date: 2014-01-27
Report

• Correlation studies for B-spline modeled F2 Chapman parameters obtained from FORMOSAT-3/COSMIC data

Limberger, Marco; Liang, W; Schmidt, Michael; Dettmering, D; Hernandez Pajares, Manuel; Hugentobler, U
Annales geophysicae
Vol. 32, p. 1533-1545
DOI: 10.5194/angeo-32-1533-2014
Date of publication: 2014
Journal article

The determination of ionospheric key quantities such as the maximum electron density of the F2 layer NmF2, the corresponding F2 peak height hmF2 and the F2 scale height HF2 are of high relevance in 4-D ionosphere modeling to provide information on the vertical structure of the electron density (Ne). The Ne distribution with respect to height can, for instance, be modeled by the commonly accepted F2 Chapman layer. An adequate and observation driven description of the vertical Ne variation can be obtained from electron density profiles (EDPs) derived by ionospheric radio occultation measurements between GPS and low Earth orbiter (LEO) satellites. For these purposes, the six FORMOSAT-3/COSMIC (F3/C) satellites provide an excellent opportunity to collect EDPs that cover most of the ionospheric region, in particular the F2 layer. For the contents of this paper, F3/C EDPs have been exploited to determine NmF2, hmF2 and HF2 within a regional modeling approach. As mathematical base functions, endpoint-interpolating polynomial B-splines are considered to model the key parameters with respect to longitude, latitude and time. The description of deterministic processes and the verification of this modeling approach have been published previously in Limberger et al. (2013), whereas this paper should be considered as an extension dealing with related correlation studies, a topic to which less attention has been paid in the literature. Relations between the B-spline series coefficients regarding specific key parameters as well as dependencies between the three F2 Chapman key parameters are in the main focus. Dependencies are interpreted from the post-derived correlation matrices as a result of (1) a simulated scenario without data gaps by taking dense, homogenously distributed profiles into account and (2) two real data scenarios on 1 July 2008 and 1 July 2012 including sparsely, inhomogeneously distributed F3/C EDPs. Moderate correlations between hmF2 and HF2 as well as inverse correlations between NmF2 and HF2 are reflected from the simulation. By means of the real data studies, it becomes obvious that the sparse measurement distribution leads to an increased weighting of the prior information and suppresses the parameter correlations which play an important role regarding the parameter estimability. The currently implemented stochastic model is in need of improvement and does not consider stochastic correlations which consequently cannot occur.

• The Baleares 2013 Calibration Campaign of Jason-2 and Saral Altimeters

Martinez Benjamin, Juan Jose; Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Gárate Pasquín, Jorge; Martin Davila, José; Perez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Gonzalez Gonzalez, Juan Carlos; Hernandez Pajares, Manuel; Salazar Lino, Mário
International GNSS Service Workshop
p. 1
Presentation's date: 2014
Presentation of work at congresses

The 2013 Balearic campaign GNSS position analysis of the 2013 will be performed with different softwares by different groups (similarly as it is being done in the International GNSS Service for their different products), in order improve the high demanded accuracy for JASON2 and SARAL altimeters precise calibration. In particular JPL GIPSY-OASIS software will be used, with the undifferenced PPP ambiguity fixing strategy. In order to improve the results accuracy, two similar networks are being processed. The first network includes the deployed GNSS receivers and the reference stations. The second one is a control network, defined by using the permanent receivers in the California dense network with a similar distribution as the main altimeter campaign network. In this case, the position of the receivers plying the role of buoys are being processed in the same kinematic way than the actual buoys, in order to compare them with the very accurate positions obtained with GIPSY-OASIS static processing.

• Impact of higher order ionospheric delay on precise GNSS computation

Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Defraigne, Pascale; Bergeot, Nicolas; Prieto Cerdeira, Roberto; Sanz Subirana, Jaime
International Colloquium Scientific and Fundamental Aspects of the Galileo Programme
p. 1-9
Presentation's date: 2013-12
Presentation of work at congresses

• UPC contribution to MONITOR Final Report

Hernandez Pajares, Manuel; Garcia Rigo, Alberto
Date: 2013-11-26
Report

• SEPsFLAREs Requirements Baseline - v1 (RB-v1)

Garcia Rigo, Alberto; Hernandez Pajares, Manuel; Nuñez, Marlon; Qahwaji, Rami
Date: 2013-11-25
Report

• SEPsFLAREs customer requirements document and review of the state of the art for SEP forecasting (CRD_REV)

Garcia Rigo, Alberto; Hernandez Pajares, Manuel; Nuñez, Marlon; Qahwaji, Rami
Date: 2013-11-25
Report

• SEPsFLAREs Solar Events Prediction system For space Launch Risk Estimation

Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Nuñez, Marlon; Qahwaji, Rami; Wahab Ahmed, Omar; Ávalos, Luciano
Competitive project

• PIOM-FIPP Precise Ionospheric Modelling For Improved GNSS Positioning in Poland

Wielgosz, Pawel; Paziewski, Jacek; Bosy, Jaroslaw; Krypiak-Gregorczyk, Anna; Hernandez Pajares, Manuel; Stepniak, Katarzyna; Hadas, Tomasz; Garcia Rigo, Alberto
Competitive project

• GIM-TEC adaptive ionospheric weather assessment and forecast system

Gulyaeva, Tamara L.; Arikan, Feza; Hernandez Pajares, Manuel; Stanislawska, Iwona
Journal of atmospheric and solar-terrestrial physics
Vol. 102, p. 329-340
DOI: 10.1016/j.jastp.2013.06.011
Date of publication: 2013-09
Journal article

• New indicator for definition of ionospheric operational conditions

Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel; Prieto Cerdeira, Roberto; Schlueter, Stefan
SBAS-IONO
Presentation's date: 2013-07-12
Presentation of work at congresses

• Definition of an SBAS ionospheric activity indicator and its assessment over Europe and Africa During the last solar cycle

Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Prieto Cerdeira, Roberto; Schlueter, Stefan
International Beacon Satellite Symposium
p. 1-4
Presentation's date: 2013-07
Presentation of work at congresses

In this work, an ionospheric activity indicator is defined based in the “weighted” Along Arc TEC rate (AATR). It is shown that this indicator, which can be easily computed from the GPS carrier phases, is well correlated with the ionospheric activity and, unlike other global indicators linked to the geomagnetic activity, can be sensitive to regional behaviours of ionospheric activity

• Higher order ionospheric delay effects and mitigation in GNSS signals for high precision applications

Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Defraigne, Pascale; Bergeot, Nicolas; Prieto Cerdeira, Roberto; Sanz Subirana, Jaime; Garcia Rigo, Alberto
International Beacon Satellite Symposium
p. 1
Presentation's date: 2013-07
Presentation of work at congresses

The significance of higher order ionospheric terms (I2+) and the performance of realistic mitigation strategies are analyzed. After confirming the unfeasibility of removing second order ionospheric term (I2) with combinations of actual data of three - frequency measurements (in coincidence with the theoretical expectations), we focus on the I2+ correction modelling from electron density and geomagnetic models, and empirical bending approximations. Using realistic simulated GNSS global observations with actual geometry (by using the IRI2012 and IGRFv11 for electron density and geomagnetic field), the impact of I2+ on high precision GNSS processing has been quantified by using independently the GIPSY and BERNESE software which provides equivalent results. The main general conclusion is that the modeling of I2+ (mainly in terms of I2, the predominant term at all the elevations, and bending corrections) can mitigate most of I2+ signature in GNSS precise geodetic products (receiver position, clock and zenith non - hydrostatic delays, satellite orbits and clocks, and geocenter estimate), which, otherwise can be significant from mm to cm level during solar cycle maximum conditions. A similar conclusion can be extended consistently to Precise Point Positioning (PPP) processing.

• North-South asymmetry in the global electron content of the Earth’s ionosphere during solstices

Gulyaeva, Tamara L.; Arikan, Feza; Hernandez Pajares, Manuel; Veselovsky, I.S.
International Beacon Satellite Symposium
p. 1
Presentation's date: 2013-07
Presentation of work at congresses

• Combination of ionospheric information

Brunini, Claudio; Azpilicueta, Francisco; Gende, Mauricio; Hernandez Pajares, Manuel; Juan, M.
International Beacon Satellite Symposium
p. 1
Presentation's date: 2013-07
Presentation of work at congresses

• Ionospheric perturbations analysis in the South East Asia Region

Garcia Rigo, Alberto; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel
International Reference Ionosphere (IRI) Workshop
p. 37
Presentation's date: 2013-06-25
Presentation of work at congresses

• Outline on gAGE/UPC on-going activities in GNSS monitoring of ionosphere

Garcia Rigo, Alberto; Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime
International Reference Ionosphere (IRI) Workshop
p. 39
Presentation's date: 2013-06-25
Presentation of work at congresses

• MONITOR CCN - Ionospheric monitoring experimentation plan and instrument development CCN

Beniguel, Yannick; Hernandez Pajares, Manuel; Garcia Rigo, Alberto
Competitive project

• GNSS Data Processing, Vol 2: Laboratory exercises , (ESA TM-23/2, May 2013)

Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel
Date of publication: 2013-05-01
Book

This two-volume book contains a self-learning course and software tools aimed at providing the necessary background to start work in an operative way in GNSS navigation. The books are focused on the instrumental use of concepts and techniques involved in GNSS navigation and include all the elements needed to understand how the system works and how to work with it. After working through the two volumes, students should be able to develop their own tools for high-accuracy navigation, implementing the algorithms and expanding the skills learned. The first volume is devoted to theory, providing a summary of GNSS fundamentals and algorithms. The second volume is devoted to laboratory exercises, with a wide range of selected practical examples going further into the theoretical concepts and their practical implementation. The exercises have been developed with a specialised software package (the ESA/U PC gLAB educational SW, on an attached CD) and selected data files are provided for the laboratory sessions.

• GNSS Data Processing, Vol1: Fundamentals and Algorithms, (ESA TM-23/1, May 2013)

Sanz Subirana, Jaime; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel
Date of publication: 2013-05-01
Book

This two-volume book contains a self-learning course and software tools aimed at providing the necessary background to start work in an operative way in GNSS navigation. The books are focused on the instrumental use of concepts and techniques involved in GNSS navigation and include all the elements needed to understand how the system works and how to work with it. After working through the two volumes, students should be able to develop their own tools for high-accuracy navigation, implementing the algorithms and expanding the skills learned. The first volume is devoted to theory, providing a summary of GNSS fundamentals and algorithms. The second volume is devoted to laboratory exercises, with a wide range of selected practical examples going further into the theoretical concepts and their practical implementation. The exercises have been developed with a specialised software package (the ESA/U PC gLAB educational SW, on an attached CD) and selected data files are provided for the laboratory sessions. This is an end-to-end GNSS course addressed to all professionals and students who wish to undertake a deeper study of satellite navigation, targeting the GNSS data processing and analysis issues.

• Feasibility of a linear model of the ionospheric scale height based on LEO GNSS occultation data

Olivares Pulido, German; Hernandez Pajares, Manuel; Aragon Angel, Maria Angeles; Sanz Subirana, Jaime
European Geosciences Union General Assembly
p. 13984
Presentation's date: 2013-05
Presentation of work at congresses

• Characterization and modelling of the ionosphere for EGNOS development and qualification

Schlüter, S.; Prieto Cerdeira, Roberto; Orús Pérez, Raul; Lam, J.P.; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel
p. 1-5
Presentation's date: 2013-04-23
Presentation of work at congresses

The availability of representative data samples, models and statistical information derived from the analysis of parameters that adequately describe the state of the ionosphere are key elements for the design, verification and qualification of EGNOS algorithms. As part of the on-going evolutions of EGNOS V2 releases, and also in support to the development of a future multi-constellation and dual-frequency SBAS (EGNOS V3), ESA has started a refinement process of the tools, data and precise definition of the ionospheric operational conditions. A particular driver for this process is the improvement of the availability performance of the current and future system especially under solar max and severe ionospheric conditions, without degradation of integrity and accuracy performances. The paper provides an overview about the concept and the data and models used for EGNOS development and qualification. It outlines the approaches to generate reference models and describes the parameter used for the characterization of nominal and perturbed ionospheric conditions from an SBAS perspective.

• Solar EUV flux rate estimation during mid and strong flares from the ionospheric electron content response signature in GNSS observations

Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Monte Moreno, Enrique; Aragon Angel, Maria Angeles
European Conference on Antennas and Propagation
p. 3675-3678
Presentation's date: 2013-04-08
Presentation of work at congresses

A simple and precise technique to measure the sudden Extreme Ultraviolet (EUV) radiation increase of the Sun, during mid and strong flares, has been formulated and demonstrated for the most active part of the last Solar Cycle. On the one hand, it is based on the short time scale of these events, which allows the validity of a simple global overionization model. And on the other hand on the prompt ionospheric response to the EUV ionization, which signature (in terms of the Global Navigation Satellite Systems -GNSSSolar Flare Activity Indicator, GSFLAI) is accurately measured in real-time from the existing global networks of dual-frequency GNSS receivers, and with a time resolution higher that those of dedicated space probes. Moreover the sensitivity of this approach enables the detection of not only extreme X-class flares, but also the detection of variations of one order of magnitude lower or even smaller (such as for M-class flares): 100% successful detection for all the X-class solar flares during 2000-2006 with registered location outside of the solar limb (i.e. detection of 94% of all of X-class solar-flares) and about 65% for M-class ones, obtained with the associated SISTED detector. In summary, its full availability, continuity, high precision and integrity for mid and high solar flare effects on Ionosphere, can make GSFLAI an useful indicator of potential Space Weather activity for many users in radio propagation. These results, which have been recently published by the authors, are extended in this work up to one complete solar cycle, and using a lower sampling rate (30 seconds), demonstrating the better behaviour of this indirect solar EUV variability proxy (GSFLAI30), when comparisons are made with direct measurements from space probes, providing readings which can be affected by the late enhancement of particles.

Gonzalez Casado, Guillermo; Juan Zornoza, Jose Miguel; Hernandez Pajares, Manuel; Sanz Subirana, Jaime
Journal of geophysical research
Vol. 118, num. 11, p. 7348-7359
DOI: 10.1002/2013JA019099
Date of publication: 2013
Journal article

A simple model for the topside ionosphere region is introduced and applied to fit radio-occultation retrieved electron density profiles for altitudes above the F2-peak. The model considers two isothermal components representing the population of the O+ (ionosphere component) and the H+ (protonosphere component) ions. The purpose of the model is to achieve an accurate fit of the observed profiles in the topside ionosphere region while, at the same time, allowing a direct and simple derivation of two important ionospheric parameters, namely, the O+ vertical scale height and the upper transition height. Covering a time period of one year, the fits with the two-component model function are compared with those achieved with one-component functions commonly used in the literature and it is shown that the former provides significantly better fits than the later, with more than a factor of two improvement. The model predictions concerning: the correlation between the O+ vertical scale height and the upper transition height, the altitude dependence of the vertical scale height of the electron density, and the quantitative contribution of the protonosphere to the total electron content are examined and shown to be consistent with the observations and with previous studies. It is concluded that the model provides a realistic description of the vertical distribution of the two main ion constituents of the topside ionosphere.

• Contributions to ionospheric determination with Global Positioning System: solar flare detection and prediction of global maps of Total Electron Content.

Garcia Rigo, Alberto
Universitat Politècnica de Catalunya
Theses

Two research studies have been addressed in this thesis. Both of them are of actual scientific interest and are based on processing GNSS data. The first part of this thesis is devoted to GNSS detection and monitoring of solar flares. The second one is devoted to GNSS prediction of ionospheric Total Electron Content. Regarding the first study, a new solar flare detector called SISTED has been designed and implemented. Its goal is to provide a simple and efficient way of detecting the most number of powerful X-class solar flares in real time operation. In addition, it can send early warning messages to prevent the harmful consequences of the increase of ejected particles from the Sun that may reach the Earth after a solar flare, especially in case of a Coronal Mass Ejection. The main benefit of SISTED regarding other detection techniques is that it does not require data from external providers out of the GNSS community. In addition, it can run in real-time operation and could provide value added data to GNSS users. The results show that SISTED was able to detect up to the 95% of the X-class flares reported by GOES for more than a half solar cycle. Regarding the second study, a new approach to predict Global Ionospheric vertical TEC Maps has been designed and implemented in the context of the IGS Ionosphere Working Group. The motivation to develop a UPC Predicted product was the interest of ESA's SMOS mission. A recent application using UPC Predicted products is the generation of real-time global VTEC maps as background model. In addition, the predicted VTEC maps are used to generate the combined IGS Predicted products. The results obtained in this thesis show that the model performs well when the results are compared with those obtained by the other IGS analysis centers. In addition, applying the prediction model leads to better results than the use of time-invariant ionosphere for two days ahead. In relation with this research, 4 publications in international journals indexed in JCR/ISI have been generated (and another one is under review process), and 7 presentations have been authored in international meetings, among the new UPC predicted product contributing to IGS, and the contribution to two competitive projects funded by the European Space Agency (AGIM and MONITOR).

• GNSS measurement of EUV photons flux rate during strong and mid solar flares

Hernandez Pajares, Manuel; Garcia Rigo, Alberto; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Monte Moreno, Enrique; Aragon Angel, Maria Angeles
Space weather: the international journal of research and applications
Vol. 10, num. 12, p. 1-16
DOI: 10.1029/2012SW000826
Date of publication: 2012-12-12
Journal article

• IONO-DeCo: executive summary of Ionospheric Delay Corrections in GNSS Signals for High Precision Applications

Aragon Angel, Maria Angeles; Hernandez Pajares, Manuel; Defraigne, Pascale
Date: 2012-12-09
Report

• Fast precise point positioning performance based on international GNSS real-time service data

Rovira Garcia, Adrià; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Hernandez Pajares, Manuel
ESA Workshop on Satellite Navigation Technologies
DOI: 10.1109/NAVITEC.2012.6423100
Presentation's date: 2012-12-05
Presentation of work at congresses

• Monitoring, tracking and forecasting ionospheric perturbations using GNSS techniques

Jakowski, N; Béniguel, Yannick; De Franceschi,, Giorgiana; Hernandez Pajares, Manuel; Jacobsen, Knut Stanley; Stanislawska, Iwona; Tomasik, Lukasz; Warnant, René; Wautelet, Gilles
Journal of Space Weather and Space Climate
Vol. 2, num. A22, p. 1-14
DOI: 10.1051/swsc/2012022
Date of publication: 2012-12-01
Journal article

The paper reviews the current state of GNSS-based detection, monitoring and forecasting of ionospheric perturbations in Europe in relation to the COST action ES0803 ‘‘Developing Space Weather Products and Services in Europe’’. Space weather research and related ionospheric studies require broad international collaboration in sharing databases, developing analysis software and models and providing services. Reviewed is the European GNSS data basis including ionospheric services providing derived data products such as the Total Electron Content (TEC) and radio scintillation indices. Fundamental ionospheric perturbation phenomena covering quite different scales in time and space are discussed in the light of recent achievements in GNSS-based ionospheric monitoring. Thus, large-scale perturbation processes characterized by moving ionization fronts, wave-like travelling ionospheric disturbances and finally small-scale irregularities causing radio scintillations are considered. Whereas ground and space-based GNSS monitoring techniques are well developed, forecasting of ionospheric perturbations needs much more work to become attractive for users who might be interested in condensed information on the perturbation degree of the ionosphere by robust indices. Finally, we have briefly presented a few samples illustrating the space weather impact on GNSS applications thus encouraging the scientific community to enhance space weather research in upcoming years.

• Ionospheric effects on GNSS performance

Béniguel, Yannick; Angling, M; Banfi, E.; Bourga, C.; Cueto, M.; Fleury, R.; Garcia Rigo, Alberto; Hamel, P.; Hartmann, R.; Hernandez Pajares, Manuel; Jakowski, Norbert; Kauristie, Kirsti; Orús Pérez, Raul; Prieto Cerdeira, Roberto; Valette, Jean Jaques; Van de Kamp, M.
IEEE Computer Society
p. 1-8
DOI: 10.1109/NAVITEC.2012.6423122
Presentation's date: 2012-12
Presentation of work at congresses

This paper presents the features of the MONITOR project. This project initiated by ESA/ESTEC aims to increase the knowledge of the ionospheric effects and its impact on GNSS systems during active periods of solar activity. It includes the deployment of a set of GNSS-based ionospheric monitoring receivers worldwide distributed, the development of specific analysis software tools some of them integrated on a common platform, others distributed providing products routinely and a measurement campaign which will last beyond the peak of the current solar cycle

• Method, apparatus and system for determining a position of an object having a Global Navigation Satellite System receiver by processing undifferenced data like carrier phase measuurements and external products like ionosphere data

Hernandez Pajares, Manuel; Juan Zornoza, Jose Miguel; Sanz Subirana, Jaime; Samson, Jaron; Tossaint, Michel Mathias Maria
Date of request: 2012-10-04
Invention patent