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International audience ; This article examines the contested process through which satellite weather data collection is being transformed from a governmental mission to one increasingly carried out by the private sector. As illustration of this controversial transformation, it addresses the debates raised in the United States between some members of the National Oceanic and Atmospheric Administration, the Congress, private firms, academic meteorology and international observers between 2006 and 2017 regarding the commercialisation of data obtained from radio occultations using the Global Navigation Satellite System. It looks, in particular, at the arguments, discourses, viewpoints and perspectives of these involved actors. By focusing on one particular site of controversy—policies and practices of data distribution—this case study emphasises a clash of values between conventional norms of meteorology and commercial imperatives driving the private sector with respects to data sharing. The main interest of this article pertains to the broader issue of changing the current model for data gathering, using and sharing in the face of growing commercialisation of weather satellites.

International audience ; This article examines the contested process through which satellite weather data collection is being transformed from a governmental mission to one increasingly carried out by the private sector. As illustration of this controversial transformation, it addresses the debates raised in the United States between some members of the National Oceanic and Atmospheric Administration, the Congress, private firms, academic meteorology and international observers between 2006 and 2017 regarding the commercialisation of data obtained from radio occultations using the Global Navigation Satellite System. It looks, in particular, at the arguments, discourses, viewpoints and perspectives of these involved actors. By focusing on one particular site of controversy—policies and practices of data distribution—this case study emphasises a clash of values between conventional norms of meteorology and commercial imperatives driving the private sector with respects to data sharing. The main interest of this article pertains to the broader issue of changing the current model for data gathering, using and sharing in the face of growing commercialisation of weather satellites.

International audience ; This article examines the contested process through which satellite weather data collection is being transformed from a governmental mission to one increasingly carried out by the private sector. As illustration of this controversial transformation, it addresses the debates raised in the United States between some members of the National Oceanic and Atmospheric Administration, the Congress, private firms, academic meteorology and international observers between 2006 and 2017 regarding the commercialisation of data obtained from radio occultations using the Global Navigation Satellite System. It looks, in particular, at the arguments, discourses, viewpoints and perspectives of these involved actors. By focusing on one particular site of controversy—policies and practices of data distribution—this case study emphasises a clash of values between conventional norms of meteorology and commercial imperatives driving the private sector with respects to data sharing. The main interest of this article pertains to the broader issue of changing the current model for data gathering, using and sharing in the face of growing commercialisation of weather satellites.

International audience ; This article examines the contested process through which satellite weather data collection is being transformed from a governmental mission to one increasingly carried out by the private sector. As illustration of this controversial transformation, it addresses the debates raised in the United States between some members of the National Oceanic and Atmospheric Administration, the Congress, private firms, academic meteorology and international observers between 2006 and 2017 regarding the commercialisation of data obtained from radio occultations using the Global Navigation Satellite System. It looks, in particular, at the arguments, discourses, viewpoints and perspectives of these involved actors. By focusing on one particular site of controversy—policies and practices of data distribution—this case study emphasises a clash of values between conventional norms of meteorology and commercial imperatives driving the private sector with respects to data sharing. The main interest of this article pertains to the broader issue of changing the current model for data gathering, using and sharing in the face of growing commercialisation of weather satellites.

International audience ; This article examines the contested process through which satellite weather data collection is being transformed from a governmental mission to one increasingly carried out by the private sector. As illustration of this controversial transformation, it addresses the debates raised in the United States between some members of the National Oceanic and Atmospheric Administration, the Congress, private firms, academic meteorology and international observers between 2006 and 2017 regarding the commercialisation of data obtained from radio occultations using the Global Navigation Satellite System. It looks, in particular, at the arguments, discourses, viewpoints and perspectives of these involved actors. By focusing on one particular site of controversy—policies and practices of data distribution—this case study emphasises a clash of values between conventional norms of meteorology and commercial imperatives driving the private sector with respects to data sharing. The main interest of this article pertains to the broader issue of changing the current model for data gathering, using and sharing in the face of growing commercialisation of weather satellites.

Abstract. Ionospheric disturbances induced by seismic activity have been studied in recent years by many authors, showing an impact both before and after the occurrence of earthquakes. In this study, the ionospheric scintillation produced by the 2021 La Palma volcano eruption is analyzed. The Cumbre Vieja volcano was active from 19 September to 13 December 2021, and many earthquakes of magnitude 3–4 were recorded, with some of them reaching magnitude 5. Three methods, GNSS reference monitoring, GNSS reflectometry (GNSS-R) from NASA CYGNSS, and GNSS radio occultation (GNSS-RO) from COSMIC and Spire constellations, are used to compare and evaluate their sensitivity as proxies of earthquakes associated with the volcanic eruption. To compare the seismic activity with ionospheric scintillation, seismic energy release, and 95th percentile of the intensity scintillation parameter (S4), measurements have been computed at 6 h intervals for the whole duration of the volcanic eruption. GNSS-RO has shown the best correlation between earthquake energy and S4, with values up to 0.09 when the perturbations occur around 18 h after the seismic activity. GNSS reference monitoring station data also show some correlation 18 h and 7–8 d after. As expected, GNSS-R is the one that shows the smallest correlation, as the ionospheric signatures get masked by the signature of the surface where the reflection is taking place. Additionally, the three methods show a smaller correlation during the week before earthquakes. Given the small magnitude of the seismic activity, the correlation is barely detectable in this situation, and thus would be difficult to use in any application to find earthquake proxies.

Intro -- Preface -- Contents -- Abbreviations -- Background and Observations -- 1 Introduction -- 1.1 History -- 1.2 Seismo-Atmospheric Anomalies -- 1.3 Seismo-Ionospheric Disturbances -- 1.3.1 Pre-seismic Ionospheric Anomalies -- 1.3.2 Co-/Post-seismic Ionospheric Anomalies -- 1.4 Summary -- References -- 2 Atmospheric Changes and Observations -- 2.1 Atmospheric Structure -- 2.2 Atmospheric Changes -- 2.2.1 Neutral Atmospheric Changes -- 2.2.2 Ionospheric Changes -- 2.3 Observation Techniques -- 2.3.1 Radiosonde -- 2.3.2 Ionosonde -- 2.3.3 Ionospheric Scatter Radar -- 2.3.4 Faraday Rotation Detection -- 2.3.5 MODIS and OLR Observations -- 2.3.6 Electromagnetic Observations -- 2.3.7 GNSS Observations -- 2.4 Solar and Geomagnetic Observations -- 2.5 Seismological Observations -- References -- 3 GNSS Tropospheric Sounding -- 3.1 Atmospheric Refractivity -- 3.2 GNSS Tropospheric Delay -- 3.3 Ground-GNSS Tropospheric Monitoring -- 3.3.1 2-D Tropospheric Monitoring -- 3.3.2 3-D Tropospheric Tomography -- 3.4 Space-Borne GNSS Radio Occultation -- 3.4.1 Refraction Index -- 3.4.2 Calculation of Total Refraction Angle -- 3.4.3 Abel Inversion -- 3.4.4 Inversion of Atmospheric Parameters -- 3.5 Other GNSS RO -- References -- 4 GNSS Ionospheric Sounding -- 4.1 Ionosphere -- 4.2 Ionospheric Delay -- 4.3 Ground-GNSS TEC Estimation -- 4.3.1 GNSS Observation Equations -- 4.3.2 GNSS Ionospheric Observations -- 4.3.3 Cycle Slip Detection -- 4.3.4 2-D Ionospheric Estimation -- 4.3.5 3-D GNSS Ionospheric Tomography -- 4.4 Space-Borne GNSS Ionospheric Monitoring -- 4.4.1 Ionosphere Inversion Based on Doppler -- 4.4.2 Ionosphere Inversion Based on TEC -- 4.4.3 Recursive Inversion of TEC -- 4.4.4 Amplitude Inversion -- References -- 5 Detection Methods for Ionospheric Disturbances -- 5.1 Detection Methods -- 5.1.1 Statistical Probability Method.

Harmful radio interference contravenes many national, regional, and international laws. Global navigation satellite system (GNSS) services have global coverage, therefore development of international law is necessary. European Union (EU) also requires harmonized law for its member states. This paper focuses on the current state of international and EU laws to tackle GNSS, radio spectrum and radio equipment usage, and probable interference with regard to location services and privacy. From a legal point of view, this paper seeks to include mitigation of unlawful interference in radio communication in order to ensure a secured location estimation and positioning system. ; Peer reviewed

GNSS signals are critically important for a wide range of commercial, military, and science applications. Recent studies have identified threats to the performance of GNSS from both intended and unintended sources of radio frequency interference (RFI). Understanding the distribution of the sources of RFI and the nature of the signals they are emitting is critical to determine and mitigate their effects on the measurements made by GNSS receivers. Terrestrial RFI can be substantially detrimental to the received GNSS signals, affecting the interpretation of related science measurements. NASA's Blackjack/TriG GNSS receivers are used for precise-orbit determination and radio occultation measurements, providing a data record spanning most of the Earth's surface for nearly 20 years. We have developed a highly sensitive detection algorithm which uses variations in the measured signal to noise ratio (SNR), on the order of 10-50 seconds, common to all satellites to identify times and locations subject to RFI. Initial work has focused primarily on detection of the presence of RFI and using the receiver's orbital solution to record the location of detection events. Our inter-mission analysis creates a unique record of global RFI with the potential for a) rigorous detection of the presence of interfering signals during science measurements, b) geolocation of RFI sources, and c) characterization of the nature of the transmitted signal to better identify intent. Preliminary analysis has shown the presence of RFI is well correlated with regional conflicts and other geopolitical activity.

This article presents a review on spaceborne Global Navigation Satellite System Reflectometry (GNSS-R), which is an important part of GNSS-R technology and has attracted great attention from academia, industry and government agencies in recent years. Compared with ground-based and airborne GNSS-R approaches, spaceborne GNSS-R has a number of advantages, including wide coverage and the ability to sense medium- and large-scale phenomena such as ocean eddies, hurricanes and tsunamis. Since 2014, about seven satellite missions have been successfully conducted and a large number of spaceborne data were recorded. Accordingly, the data have been widely used to carry out a variety of studies for a range of useful applications, and significant research outcomes have been generated. This article provides an overview of these studies with a focus on the basic methods and techniques in the retrieval of a number of geophysical parameters and the detection of several objects. The challenges and future prospects of spaceborne GNSS-R are also addressed.

The aim of this paper is to trigger a conversation about the assessment, definition of metrics and testing procedures of software-defined GNSS receivers. While the evaluation of traditional (i.e., built on application–specific integrated circuit technology) GNSS receivers is now well–understood, and enjoys both a solid testing industry providing the required equipment and universally agreed figures of merit, the particularities of software–defined radio technologies claim for a more comprehensive approach. In order to account for such a multi–faceted nature, the authors identify sixteen design forces, or dimensions in which a software-defined GNSS can improve. Upon those definitions, a wide list of performance indicators, metrics and procedures are then proposed for each of the identified thrusts. The list can be used as a generative source of ideas when defining key performance indicators in projects, products or services involving a software–defined GNSS receiver. ; Grant numbers : Authors were also support by the Government of Catalonia under Grant 2014–SGR–1567.

There are three main activities of General Directorate of Land Registry and Cadastre. These are Mapping, Land Registry and Cadastre. Geomatic Department is responsible for mapping activities. The most important projects like TUSAGA-Aktif (CORS-Tr), Metadata Geoportal, Orthophoto Production and orthophoto web services and preparation of Turkish NSDI Feasibility Report have been conducted and completed by this department's specialists since 2005. TUSAGA-Aktif (CORS-Tr) System, serves location information at cm level accuracy in Turkey and TR Nortern Cyprus in few seconds, where adequate numbers of GNSS satellites are observed and communication possibilities are present. No ground control points and benchmarks are necessary. There are 146 permanent GNSS stations within the CORS-Tr System. Station data are transferred online to the main control center located in the Mapping Department of the General Directorate of Land Registry and Cadastre and to the control center located in the General Command of Mapping. Currently CORS-Tr has more than 9000 users. Most of them are private companies working for governmental organization. Providing data communication between control center and both GNSS station and users via trusted and good substructure is important. Additionally, protection of the system and data against cyber attacks from domestic and foreign sources is important. This paper focuses on data communication and security issues of GNSS network named TUSAGA-Aktif.

There are three main activities of General Directorate of Land Registry and Cadastre. These are Mapping, Land Registry and Cadastre. Geomatic Department is responsible for mapping activities. The most important projects like TUSAGA-Aktif (CORS-Tr), Metadata Geoportal, Orthophoto Production and orthophoto web services and preparation of Turkish NSDI Feasibility Report have been conducted and completed by this department's specialists since 2005. TUSAGA-Aktif (CORS-Tr) System, serves location information at cm level accuracy in Turkey and TR Nortern Cyprus in few seconds, where adequate numbers of GNSS satellites are observed and communication possibilities are present. No ground control points and benchmarks are necessary. There are 146 permanent GNSS stations within the CORS-Tr System. Station data are transferred online to the main control center located in the Mapping Department of the General Directorate of Land Registry and Cadastre and to the control center located in the General Command of Mapping. Currently CORS-Tr has more than 9000 users. Most of them are private companies working for governmental organization. Providing data communication between control center and both GNSS station and users via trusted and good substructure is important. Additionally, protection of the system and data against cyber attacks from domestic and foreign sources is important. This paper focuses on data communication and security issues of GNSS network named TUSAGA-Aktif.