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Existing climatological ionosphere models, for example, GISM, SCIONAV, WBMOD, and STIPEE, have known limitations that prevent their wide use. In the framework of ESA study “Radio Climatology Models of the Ionosphere: Status and Way Forward” their performance was assessed using experimental observations of ionospheric scintillation collected over the past years to evaluate their ability to properly support future missions, and eventually indicate their weaknesses for future improvements. Model limitations are more important in terms of the intensity scintillation parameter (S4). To improve them, the COSMIC model has been fit (scaling factor and offset) to the measured data, and it became the one better predicting the intensity scintillation in a statistical sense. This research was funded by the project “Radio Climatology Models of the Ionosphere: Status and Way Forward,” ESA/ESTEC, grant number 4000120868/17/NL/AF [https://nebula.esa.int/content/radio-climatology-models-ionosphere-status-and-way-forward]. Article processing charges were funded by the project “GENESIS: GNSS Environmental and Societal Missions – Subproject UPC,” AEI Grant PID2021-126436OB-C21.

onospheric scintillation consists on rapid fluctuations in the amplitude and phase of electromagnetic signals, which includes those of the Global Navigation Satellite System (GNSS), that can lead to cycle slips and even to a loss of lock on the receiver tracking. Hence, scintillation has become one of the major concerns in navigation and the detection and/or mitigation of its effects is one of the current challenges in achieving precise GNSS navigation. This study is focused in characterizing the ionospheric scintillation phenomenon mainly at high latitudes, although one mid-latitude and one low-latitude station have been included in order to compare the results obtained and to be able to correlate the Total Electron Content (TEC) fluctuations with phase scintillation at all latitudes. This characterization has been done based on the parameters σϕ, ROT IL1 and ROT ILGF , using a database of two years of data, 2014 and 2015, and dividing each of them into three different periods (January to April, May to August, and September to December) in order to better assess the levels of scintillation at each station of the year. Moreover, the results obtained using the signals from two different GNSS satellite constellations (GPS and GLONASS) have been studied and compared. The thresholds for moderate and intense scintillation have been computed from the Cumulative Distribution Functions (CDF) of each scintillation for each station, year, period of the year and GNSS satellite constellation using each parameter at 99% and 99.9% percentiles for moderate and intense levels of scintillation, respectively. Thus, using these thresholds and also using the 1-CDF plots, the seasonal evolution of parameters σϕ and ROT IL1 has been analyzed for different stations per constellation. Furthermore, the correlation between both ROT I parameters and σϕ has been assessed for each station, constellation, year and period of the year. It has been observed that these correlation indexes highly depend on the model of the receiver, location of the receiver and the type of constellation used, fact that will help to differentiate between the level of scintillation measured for different receivers per constellation. The scintillation phenomenon has been observed to depend on: the location of the receiver, period of the year, model of the receiver, GNSS satellite constellation, and obviously the ionosphere behaviour. Finally, the parameter ROT IL1 has been observed to perform better than ROT ILGF at high-latitude stations.

As the world becomes more complex rapidly having a smart infrastructure is a necessity to be able to manage them remotely by high accuracy. In order to cope with this issue we need to have precise navigation globally which could be challenging in high- and low latitudes then the focus here is on six GNSS (Global Navigation Satellite System) receivers in the arctic region (high latitude) with GLONASS and GPS constellations. The impact of ionospheric scintillation has been characterized based on Sigma Phi, AATR and ROTI, using a database of one year of data in 2014. The thresholds from cumulative distribution function (CDF) of those scintillation parameters at 99% and 99.9% for each station per constellation have been extracted and high scintillation events were detected. The 1-CDF plots of December and July were compared and the seasonal Sigma Phi evolution has been analyzed for different stations per constellation. Moreover the linear correlation between ROTI and Sigma Phi was observed. These correlation indexes highly depend on type of the receiver, location of the receiver and the type of constellation used which will help us to differentiate between the level or impact of scintillation measured for different receivers per constellation. The scintillation events are observed to depend generally on the location of the receiver, period of the day, performance of the receiver, satellite constellation, and ionosphere behaviour. In addition, the impact of data loss in the database analysed has been shown to be relevant and different from station to station. Finally, single frequency PPP could have a higher convergence time in comparison with double frequency PPP according to a preliminary study. Hence, a detailed future work to investigate this issue is proposed.

In this project, the study of a methodology for the computation of a reliable estimation sigma_pr_gnd is study. The method presented is intended to be used for the calibration of the GBAS station, using only one day of data. The GBAS station is used for aircraft navigation in the vicinity of an airport, being used for the precision approaches and landing of the aircraft.