# Monitoring of Ionospheric Anomalies Using GNSS Observations to Detect Earthquake Precursors
## 5 Conclusions  
Space weather monitoring is presently a crucial activity supporting radio communications as well as navigation. Ionospheric anomalies are events which can significantly impact this task. One of the most important causes of the anomalies is the effect of the interaction between the solar activity and the magnetic activity; however, there is another cause of anomalies, which is correlated with notable geophysical events such as earthquakes.  
To comprehensively determine space weather, it is important to detect these anomalies and, at the same time, to obtain information about the phenomena that produce them. GNSS observations are widely used for this scope, including GIMs and VTEC time series, as well as derived products like the DTEC, ROT, and ROTI, provide information about the ionosphere status. The processing of GNSS Doppler observations in real-time can give us other useful information to detect ionospheric anomalies. For this reason, the VTEC, VTEC rate, and VTEC rate SNR were produced in this work, and the analysis of their time series (for a specific point of the ionospheric layer), as well as their maps,was used to detect ionospheric tracks of solar activity and tracks of interactions between Earth's magnetic field and the ground level in a geophysical active zone. As a result, some possible tracks of anomalies were detected. As the ionosphere is a dynamic system with a complex evolution in space and time, influenced and modified by causes of terrestrial and extraterrestrial origin, an anomaly can sometimes appear over areas that are not necessarily geologically active. Among all the possible anomalies revealed by maps, these overlapping geological faults should be considered first. The fact that anomalies can be detected in maps by referring to different parameters (DTEC, DSNR, etc.) can be lead to a strategy to identify those actually related to earthquakes. The anomalies correlated with the earthquake preparation phase can be identified by analyzing the values of different parameters (VTEC, DTEC, VTEC rate, SNR, etc.). A possible future development of the research will be to consider the possibility of cataloging the potential anomalies correlated with earthquakes on the basis of the values of these parameters, with the aim of verifying the presence of regularities in their manifestation.  
Apart from the results obtained, it is necessary to remark that an increased number of CORSs is needed to improve the robustness of the model, primarily wherever the coverage of permanent stations is currently poor (e.g., Africa and some parts of Asia). This goal can be theoretically reached within the continents but not over the ocean surfaces, for which a different measurement technique (not necessarily involving GNSS stations) should perhaps be identified.  
Conceptualization, N.P.; methodology, N.P. and Y.T.; software, N.P. and Y.T.; validation, N.P.; formal analysis, N.P.; investigation, N.P., Y.T., and A.P.; resources, N.P. and A.P.; data curation, N.P.; writing--original draft preparation, N.P. and Y.T.; writing--review and editing, N.P. and Y.T.; visualization, N.P. and Y.T.; supervision,