Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TechTIDE (Warning and Mitigation Technologies for Travelling Ionospheric Disturbances Effects)

Teaser

The Earth\'s upper atmosphere is directly affected by the solar variability, by the near-Earth space dynamics and by lower atmosphere phenomena. This, results in a complex and dynamic environment influenced by solar radiation, energy transfer, winds, waves tides, electric and...

Summary

The Earth\'s upper atmosphere is directly affected by the solar variability, by the near-Earth space dynamics and by lower atmosphere phenomena. This, results in a complex and dynamic environment influenced by solar radiation, energy transfer, winds, waves tides, electric and magnetic fields, and plasma processes.
Travelling Ionospheric Disturbances (TIDs) are an important Space Weather effect in the upper atmosphere driven by this complexity. TIDs are plasma density fluctuations that propagate as waves through the ionosphere at a wide range of velocities and are associated with auroral and geomagnetic activity and with lower atmosphere phenomena of non-space origin (e.g., severe tropospheric convection or passages of cold fronts, seismicity, volcanic activity, and artificially triggered events such as explosions).
TIDs constitute a threat for operational systems using predictable ionospheric characteristics as they can impose disturbances with amplitudes of up to ~20% of the ambient electron density, and a Doppler frequency shifts of the order of 0.5 Hz on HF signals. The last years it was clearly demonstrated that TIDs can have multiple effects in the operation of aerospatial and ground-based infrastructures and especially in the European Geostationary Navigation Overlay Service (EGNOS) and Network Real-Time Kinematic (N-RTK) services, in High Frequency (HF) communications, in radio reconnaissance operations and in Very High Frequency – Ultra High Frequency (VHF-UHF) radiowave propagation. Despite these important effects in the reliable operation of infrastructures that are critical for the safety and security of the citizens, the identification and tracking of TIDs is very complicated and has not been achieved in operational service mode.
TechTIDE comes to fill in this gap. Its overarching objective is to design and test new viable TID impact mitigation strategies for the technologies affected by the TIDs and in close collaboration with operators of these technologies, to demonstrate the added value of the proposed mitigation techniques which are based on TechTIDE products.

Work performed

Within this first reporting period, the consortium completed a detailed survey of users’ requirements, concerned mainly with users of HF operations, of GNSS and EGNOS services, and users of N-RTK services. These initial user requirements have been reviewed, prioritized and categorized to extract functional and non-functional requirements.
The following main TID identification algorithms have been upgraded and adjusted to the users’ requirements :
1. HF-TID is based on detection of quasi-periodic oscillations that the HF signal exhibits as it propagates a trans-ionospheric channel that is modulated by TID perturbations (Figure 1).
2. HF Interferometry identifies LSTIDs for a network of Ionosondes. It detects quasi-periodic oscillations of ionospheric characteristics and identifies coherent oscillation activity (Figure 2).
3. Spatial and Temporal analysis of GNSS measurements allows the detection and characterization of MSTIDs and LSTIDs, including velocity and period (Figure 3).
4. TEC gradients is a method applied to detect LSTIDs occurring during geomagnetic storms. In such conditions, strong temporal and spatial TEC gradients are observed closest to the source region of LSTIDs (Figure 4).
5. The 3D EDD method is based on the reconstruction of the 3D electron density distribution (EDD), developed on the basis of the Topside Sounding Model-assisted Digisonde (TaD) profiler. It ingest Digisondes and GNSS data and it is sensitive to LSTIDs (Figure 5).
6. The height-time-reflection intensity (HTI) methodology uses a sequence of ionograms to compute an average HTI plot (Figure 6).
7. The CDSS – multipoint Continuous Doppler Sounding System (CDSS) method is able to detect fluctuations of the Doppler shift of the transmitted frequencies caused by the TIDs passing over reflection point and to estimate MSTIDs characteristics (Figure 7).
8. Along Track TEC Rate (AATR) indicator is used to identify the conditions of degradation in the performance of the SBAS (EGNOS) systems (Figure 8).

The basic software codes are made available with open access through the TechTIDE repository, and most of the TID identification methodologies are implemented to run routinely and provide products and value-added results.

In parallel important developments were achieved in defining the TID drivers for medium and large-scale activity, in assessing the criticality of the prevailing conditions, and in evaluating the interhemispheric circulation as an additional mechanism of secondary intensification of TIDs.
In this reporting period, the IT TechTIDE warning system is designed and parts of it are under development. The plan is to release the first version of the TechTIDE prototype system by April 2019. This first version will make available results from the TID identification codes. The first TechTIDE release will be demonstrated in the first user workshop (on 15 May 2019 in DLR). In this workshop, the consortium will discuss with potential users on specific events where performance degradation is identified in the analysis of data collected from N-RTK, EGNOS and HF operations and compared with the results of TID identification methodologies.

Final results

The progress achieved by TechTIDE clearly goes beyond the state of the art:
1. TechTIDE provides for the first-time direct identification of TIDs in real-time based on different and complementary detection techniques based on data from Digisondes, from GNSS receivers and from Doppler Soundings.
2. TechTIDE specified the drivers for Medium Scale and Large Scale TIDs and based on this has improved our understanding of Space Weather phenomena (SW) and especially of phenomena that lead to the generation of the different types of TIDs triggered by disturbances in the solar wind – magnetosphere – atmosphere coupled system.
3. TechTIDE analysed data from Digisondes, GNSS receivers and Doppler Soundings simultaneously collected from experiments operated in Europe and South Africa regions to support novel studies on the TID triggering mechanisms including their intensification due to interhemispheric circulation.
4. TechTIDE collected users’ requirements for the development of a comprehensive TID detection system, complementary to the services currently delivered by the ESA SSA Space Weather Programme.
Within the remaining period the consortium will develop the TechTIDE warning system in three phases. Each phase includes a users’ workshop that has the aim to assess the suitability of the warning system products and services, in respect to the operational requirements. The final phase will be the most important because we will also verify the ability of the warning system to provide products that can be included in the mitigation chain of the operators of aerospace and ground-based system affected by TIDs.
TechTIDE is expected to achieve all the impacts foreseen in the proposal submission phase. It is expected to improve the understanding of Space Weather phenomena and especially of phenomena that lead to the generation of the different types of TIDs; It is expected to improve the understanding of the impact of TIDs on systems directly affected, i.e. EGNOS services, N-RTK and HF operations. It is expected to support the design of mitigation strategies bringing a clear benefit on quality of critical operations and services.

Website & more info

More info: http://tech-tide.eu/.