The main objective of the present study is to perform an analysis of the space weather impact on the Latvian CORS (Continuously Operating GNSS (Global Navigation Satellite System) Stations) GPS (Global Positioning System) observations, in situations of geomagnetic storms, sun flares and extreme TEC (Total Electron Content) and ROTI (Rate of change of TEC index) levels, by analyzing the results, i.e., 90-s kinematic post-processing solutions, obtained using Bernese GNSS Software v5.2. To complete this study, the 90-s kinematic time series of all the Latvian CORS for the period from 2007 to 2017 were analyzed, and a correlation between time series outliers (hereinafter referred to as faults) and extreme space weather events was sought. Over 36 million position determination solutions were examined, 0.6% of the solutions appear to be erroneous, 0.13% of the solutions have errors greater than 1 m, 0.05% have errors greater than 10 m, and 0.01% of the solutions show errors greater than 50 m. The correlation between faulty results, TEC and ROTI levels and Bernese GNSS Software v5.2 detected cycle slips was computed. This also includes an analysis of fault distribution depending on the geomagnetic latitude as well as faults distribution simultaneously occurring in some stations, etc. This work is the statistical analysis of the Latvian CORS security, mainly focusing on geomagnetic extreme events and ionospheric scintillations in the region of Latvia, with a latitude around 57°N.

The geomagnetic storm on 17 March 2015 had a strong impact on the global navigation satellite systems (GNSS) positioning results in many GNSS Continuously Operating Reference Stations (CORS) in Europe. The analysis of global positioning system (GPS) observations in Latvian CORS stations discovered a strong impact of this space weather event over the whole country. The impact appeared as a moving cloud of positioning discrepancies across the country. However, the analysis of the days before 17 March revealed other smaller duration ionospheric scintillation events. The objective was to analyze the GPS positioning discrepancy cloud movement, total electron content (TEC), and rate of change of the TEC index (ROTI) relationships, as well as discrepancy statistics. The area of analysis on 16–18 March was increased by including the EGNOS ground-based Ranging and Integrity Monitoring Stations (RIMS): GVLA and GVLB, LAPA and LAPB, and WRSA and WRSB. The conclusion of the study is that each “shot” after 90 s gives a completely new cloud with a new impacted station subset, its configuration, and completely irregular discrepancy values.

The aim of this study was to find out whether, just like in March 2015, daily regular GPS positioning disturbances caused by ionospheric scintillations occurred in other months of the solar activity cycle 24. The GPS positioning 90-s kinematic solutions of selected 46 months covering 11 years were used to search for regular daily scintillation events. The hypothesis on predictable regular daily ionospheric scintillation was tested. Scintillation waves were discovered as a result of space weather impact with the sidereal day regularity. It leads to the conclusion that the radiation originates from the interplanetary medium. The enhancement of radiation waves by solar activity is similar to Pc1 waves. The regular daily ionospheric scintillation waves are recorded at any time of the day. In the years with low solar activity in 2010 and 2012, regular scintillation waves were not found. It cannot be claimed that the comparison of daily regular ionospheric scintillation cases over time with the mentioned Pc1 wave cases indicates any interrelation.

The main objective of the present study is to perform analysis of the space weather impact in the cases of each day periodic occurrence in various seasons in selected monthly nights at the GPS positioning results of Latvian CORS (Continuously Operating Reference Stations) in time span 2007 to 2017. The analysis performed of the GPS (Global Positioning System) 90-second kinematic post-processing solutions, obtained using Bernese GNSS Software v5.2. To complete this study, the time series of daily outliers are analyzed for all the Latvian CORS that occurs simultaneously in two or more CORS stations. Over 36 million position determination solutions were examined. Daily regular ionospheric scintillation phenomena with duration around 4-7 minutes were observed in solar activity years daily, starting from March till December. The research articles were searched where similar scintillation events have been analyzed. The articles on Pc1 scintillation waves were found where similar phenomena has been described. The results of statistical analysis of the occurrence events will be presented, focusing especially on the periodic ionospheric scintillations observed in the region of Latvia, with a latitude around 57º N.

The aim of this study was to find out whether, just like in March 2015, daily regular GPS positioning disturbances caused by ionospheric scin tillations occurred in other months of the solar activity cycle 24. The GPS positioning 90-sec kinematic solutions of selected 46 month covering 11 years were used for search of regular daily scintillation events. The hypothesis on predictable regular daily ionospheric scintillation was tested. Discovered scintillation waves as a result of space weather impact with the siderial day regularity. It leads to conclusion of the radiation origin from the interplanetary media. The enhancement of radiation waves by solar activity is similar as it is for Pc1 waves. The regular daily ionospheric scintillation waves are recorded at any time of the day. In years of low solar activity in 2010 and 2012, regular scintillation waves were not found. It cannot be claimed that the comparison of daily regular ionospheric scintillation cases over time with the mentioned Pc1 wave cases indicates any interrelation.