Travelling ionospheric disturbances (TIDs) play an important role in spreading radio signals across Earth’s ionosphere. They propagate as waves through the ionosphere at a wide range of velocities and frequencies. TIDs can cause disturbances to the operation of aerospatial and ground-based infrastructures, especially the European Geostationary Navigation Overlay Service (EGNOS) and network real-time kinematic (NRTK) services, as well as to high-frequency communications and radio reconnaissance operations. “TIDs occur almost daily,” explains Anna Belehaki, coordinator of the EU-funded TechTIDE project. “Identifying and tracking them is very complicated, and this has yet to be achieved in operational service mode.”
Warning services for systems in space and on Earth
Project partners designed, tested and validated new, viable TID impact mitigation strategies for technologies that are directly affected. They closely collaborated with operators of these technologies to demonstrate the added value of the proposed mitigation techniques for EGNOS, NRTK and high-frequency operations. The developed methodologies are able to support for the first time the direct, real-time identification and tracking of TIDs over vast world regions. These detection methodologies were implemented online with real-time data. The results were calculated in near-real time. All software codes for TID identification have been released in open access. The TechTIDE team created a web-based system to issue warnings of TID occurrence over the area that extends from Europe to South Africa. It provides 70 different products to support users, and handles data and products from 21 different data providers. The open-access products are available in real time, and archived data is accessible via the TechTIDE API. The system estimates the parameters that specify TID characteristics, and it provides all additional geophysical information to users to help them assess the risks and develop mitigation techniques tailored to their applications. In this way, aerospatial and ground-based communication systems operators become aware of the threats TIDs pose to their systems. As a result, they can develop mitigation technologies supported by the TechTIDE real-time warning solution.
Greater insight into effect of TIDs
By systematically comparing TID predictions with performance degradation data, project partners were able to specify the impact under different solar cycle phases, seasons, local times and solar wind-magnetosphere coupling conditions. Their research efforts enabled them to better understand phenomena that lead to the generation of different types of TIDs triggered by disturbances in solar wind and in the lower atmosphere. “This achievement, together with the development of innovative nowcasting techniques, lays the groundwork for the development of TID forecasting models that are a key requirement for any high-accuracy space weather service,” notes Belehaki. In collaboration with potential users such as the European Space Agency, project partners assessed the functionality, reliability and efficiency of the proposed services, paving the way to their systematic exploitation and sustainable operation. “TechTIDE has improved our understanding of the physical processes resulting to the formation of TIDs through the identification of drivers in the interplanetary medium, the magnetosphere and the atmosphere,” concludes Belehaki. “The results contributed to identifying the impact of TIDs on space-based navigation systems, mainly EGNOS and NRTK, and on ground-based, high-frequency communication and geolocation systems.”
TechTIDE, TID, space, EGNOS, NRTK, ionosphere, high-frequency communication, travelling ionospheric disturbance, ground-based infrastructure